Harlan Ellison has done a rather large amount of writing:

Web of the City (1958)
The Sound of a Scythe (1969)
Spider Kiss (Originally titled "Rockability") (1961)

Graphic Novels
Demon with a Glass Hand (Adaptation with Marshall Rogers) (1986)
Night and the Enemy (Adaptation with Ken Steacy) (1987)
Vic and Blood: The Chronicles of a Boy and His Dog (Adaptation with Richard Corben) (1989)
Harlan Ellison's Dream Corridor Volume One (1996)

Short Novels
Doomsman (1967)
All The Lies That Are My Life (1980)
Run for the Stars (1991)
Mefisto in Onyx (1993)

Short Story Collections
The Deadly Streets (1958)
Sex Gang (As Paul Merchant) (1959)
A Touch of Infinity (1960)
Children of the Streets (1961)
Gentleman Junkie and Other Stories of the Hung-Up Generation (1961)
Ellison Wonderland (1962)
Paingod And Other Delusions (1965)
I Have No Mouth and I Must Scream (1967)
From The Land of Fear(1967)
Love Ain't Nothing But Sex Misspelled (1968)
The Beast That Shouted Love at the Heart of the World (1969)
Over the Edge (1970)
Approaching Oblivion (1974)
Deathbird Stories (1975)
No Doors, No Windows (1975)
Strange Wine (1982)
Shatterday (1980)
Stalking the Nightmare (1982)
Angry Candy (1988)
Jokes Without Punchlines (1995)
Slippage (1997)
Troublemakers (2002)

Omnibus Volumes
The Fantasies of Harlan Ellison (1979)
Dreams with Sharp Teeth (1991)
Edgeworks Volume 1 (1996)
Edgeworks Volume 2 (1996)
Edgeworks Volume 3 (1997)
Edgeworks Volume 4 (1997)

Non-Fiction and Essays
Memos From Purgatory (1961)
The Glass Teat (1970)
The Other Glass Teat (1975)
The Book Of Ellison (1978)
Sleepless Nights in the Procrustean Bed (1984)
An Edge in My Voice (1985)
Harlan Ellison's Watching (1989)
The Harlan Ellison Hornbook (1990)

Alone Against Tomorrow: A Ten Year Survey(1971)
The Essential Ellison: A 35-Year Retrospective (Edited by Terry Dowling, with Ricard Delap and Gil Lamont) (1987)
The Essential Ellison: A 50-Year Retrospective (Edited by Terry Dowling, with Ricard Delap and Gil Lamont) (2001)

Comic Books
He wrote the following comic books, he didn't draw them, or have anything to do with the artwork...
Creepy #32 (1970) - "Rock God"
Avengers #88 (1971) - "The Summons of Psyklop (In the Grip of Psyklop, part 1)"
Incredible Hulk #140 (1971) - "The Brute, or The Brute That Shouted Love at the Heart of the World"
Avengers #101 (1972) - "Five Dooms to Save Tomorrow"
Chamber of Chills #1 (1972) - "Delusion for a Dragon Slayer"
Harlan Ellison's Chocolate Alphabet (1978)
Daredevil #208 (1984) - "The Deadliest Night of My Life"
Daredevil #209 (1984) - "Blast From the Past"
Heroes For Hope starring the X-Men (1985) - pp 22-24

(I took this list from Harlan Ellison's website (http://harlanellison.com), and he doesn't mention the years he wrote them. He does mention who he wrote it for, so I guess I'm leaving that in.)
Would You Do It For a Penny?Playboy Productions
Stranglehold20th Century Fox / Marvin Schwartz Productions
Harlan Ellison's Movie20th Century Fox /Marvin Schwartz Productions
Blind Voices – Jay Julian
Seven Worlds, Seven Warriors - Filmation / Dino De Laurentiis
The Whimper Of Whipped Dogs – William Friedkin / ITC
I, Robot – Edward Lewis Productions / Warner Bros.
(Note: I know an illustrated version of this screenplay was published.)
A Boy And His Dog –L. Q. JAF Productions
(I like how The Internet Movie Database lists this to be also known as "Psycho Boy and His Killer Dog"...)
Nick The Greek – Jan Grippo Productions
Best By Far – James Harris Productions
Swing Low, Sweet Harriet – Palomar / MGM
Valley Of The DollsFox
The OscarParamount (Embassy)
The Dream MerchantsParamount (Embassy)
RumbleAmerican International
KhadimParamount / Joseph E. Levine
Bug Jack BarronUniversal / Costa-Gavras / Lewis Productions

Television Features, Pilots and Long Forms
(Again, this list is taken directly from Ellison's website. I did reformat it slightly. So, um, I'm doing a bit of work here. Ok, not really. It's still useful information.)
Tired Old Man – Joel Cohen, David Soul
Heavy MetalUniversal
A Boy And His DogNBC-TV (Pilot)
The Spirit – William Friedkin / NBC-TV (Pilot)
Mystery Show
Dark DestroyerABC-TV
The Starlost20th Century Fox / CBS
The Dark ForcesScreen Gems / NBC-TV
Our Man Flint20th Century Fox
Astral Man – Herb Solow / Universal
Man Without TimeParamount / NBC-TV
Astra/Ella - Paramount
The Other PlaceUniversal / ABC-TV
Project 120Universal
Bring ’Em Back Alive – Sy Weintraub Productions
Postmark: Jim Adam – Screen Gems
The Contender – Bruce Geller / Bernard Kowalski / Screen Gems
The Sniper
Brillo – Alan Landsburg Productions / NBC-TV
The Tigers Are Loose – Alpine / NBC-TV
Cutter’s World - NBC / New Horizons Films (Roger Corman)

Episodic Television
(He doesn't specify which episodes he wrote, so, the ones mentioned are courtesy of IMDB and fansites, and are in quotations.)
Alfred Hitchcock Presents (1955) ("Memos from Purgatory" Side note: This starred James Caan (Best known as Sonny Corleone from The Godfather) as Harlan Ellison.)
The Untouchables (1959 - 63)
The Twilight Zone (1959 - 64) - ("Gramma", "Crazy as a Soup Sandwich", "One Life, Furnished in Poverty", "Palladin of the Lost Hour", "Shatterday")
Route 66 (1960) - ("A Gift for a Warrior")
Ripcord (1962) - ("Where Do Elephants Go to Die?")
Bob Hope Chrysler Theatre (1963 - 67)
The Great Adventure (1963 - 64)
The Outer Limits (1963) - ("Demon with a Glass Hand" & "Soldier" As a sidenote, The movie The Terminator is based off of these...)
Burke’s Law (1963-65) / Amos Burke, Secret Agent (1965 - 66) - ("Who Killed 1/2 of Glory Lee?", "Who Killed Purity Mather?", "Who Killed Alex Debbs?", "Who Killed Andy Zygmunt?")
Voyage to the Bottom of the Sea (1964) - ("The Price Of Doom")
The Man From U.N.C.L.E. (1964 - 68) - (Did an uncredited "polish" of "The Virtue Affair", wrote "The Sort-of-Do-It-Yourself Dreadful Affair", "The Pieces of Fate Affair")
Honey West (1965 - 66)
Batman (1966 - 68)
Rat Patrol (1966)
Cimarron Strip (1967) - ("Knife in the Darkness")
The Flying Nun (1967) - ("You Can't Get There from Here")
Star Trek (1967) - ("The City on the Edge of Forever")
The Name of the Game (1968 - 71)
The Young Lawyers (1970) - ("Whimper of Whipped Dogs")
The Sixth Sense (1972) – Creative Consultant
Ghost Story: Circle of Fear(1973) - ("Earth, Air, Fire And Water" with D. C. Fontana)
The Starlost (1973 - 74)
Manhunter (1974 - 75)
Logan's Run (1977) - ("Crypt")
Babylon 5 (1993 - 99) – Conceptual Consultant (1993 – 1998)
The Hunger (1997) – Showtime
Tales from the Darkside (1984) - ("Djinn, No Chaser")
Dark Room ?
Empire ?

He has some acting credits as well
The Godson (1971)
The Masters of Comic Book Art (1987) (Narrator)
I Have No Mouth, and I Must Scream (1995) (Video Game) (voice of AM)

Let's not forget he made Records, too
On The Road With Ellison (1983) (This was originally a limited edition vinyl release, Deep Shag Records rereleased it in 2001.)
The Voice from the Edge (Volume 1) (1999)
Midnight in the Sunken Cathedral (2001)

It probably doesn't deserve a node of its own, so I'll note it here. The Edgework's series (Under "Omnibus Volumes") was a projected 20 volume reprinting of Ellison's work by White Wolf Publishing (Yes, the same people who do Vampire: The Masquerade). Each volume contains 2 of his older books, for the price of one. Which is keen, and you should go buy them all now. Anyway, as far as I know, only four of these books were released, all in hardcover, though, the first two were released in softcover additions as well. Edgeworks Volume 1 contains Over the Edge and An Edge in My Voice. Volume 2 contains Spider Kiss and Stalking the Nightmare. Volume 3 contains The Harlan Ellison Hornbook and Harlan Ellison's Movie (which was never actually released before as a book, except in limited editions of the Hornbook, it's an experimental series of Hornbook entries that make up a movie. That, of course, was never made). Volume 4 contains Love Ain't Nothing but Sex Misspelled and The Beast That Shouted Love at the Heart of the World.

What I find amusing about these reprints is the fact that each volume has a new introduction, and each individual book has an introduction. But, some of the books are reprints of the (relatively) newer editions, so they contain the newer introductions as well (for example, I believe Neil Gaiman wrote an introduction to The Beast That Shouted Love at the Heart of the World in Vol 4). The end result being, the books have at least 3 introductions each, some with four or five, I believe. That's ok, though. Harlan Ellison writes a mean introduction.

Since I mention all of his work on TV shows, I thought I'd also mention the fact that Ellison once sued ABC-TV and Paramount Pictures for plagiarizing Brillo. Or Future Cop. Which ever one he made. I'm uncertain, as all I could find on the supposedly famous "Brillo/Future Cop" case were the sentences, "In a 1980 landmark lawsuit he sued and beat ABC-TV and Paramount Pictures for $337,000 when they plagiarized a television series he had created. This was the famous Brillo/Future Cop case." The funny thing is, three different websites, (http://harlanellison.com/bioreal.htm, http://web.mit.edu/lsc/www/fiction/ellison.html, http://www.deepshag.com/ellison.html) all have those exact same sentences without citing, so someone is plagiarizing someone. Again. The irony.

Update: DejaMorgana tells me that Brillo was originally a short story co-authored with Ben Bova, collected in Partners in Wonder. Many thanks. TV Tome (http://www.tvtome.com/) tells me that Future Cop was an ABC series starting in 1976 that ran for just under a year, which seems strange, as the sites said the lawsuit was in 1980. Of course, this is entirely possible, so maybe Ellison was just lazy, or waits a few years before checking out reruns.

Sources: My various Harlan Ellison books, Ellison's website (http://harlanellison.com), the Internet Movie Database, http://www.manfromuncle.org, http://www.snowcrest.net/fox/logantv/, http://www.tvtome.com, uh, and a bunch of other fansites that I didn't copy down....