Fleas are amazing, nearly indestructible little freaks of nature. They (as I learned this morning from a fellow noder) build up immunities to insecticides and in fact evolve to flourish in environments full of certain types of chemicals (damn the little bastards!) which renders a once-effective flea killing agent no good at all after a few seasons. Worse, they cause endless kinds and shapes of discomfort and ickiness for you and your family's pets.

Tapeworms are transmitted by fleas. Here's how it goes: Rover has fleas. Being a dog, he scratches at himself with his little front teeth, thereby ingesting one of the blasted offenders. Said ingested offender has tapeworm eggs in its belly. Eggs hatch inside Rover, and hurrah, you've got a tapeworm infestation. (Characterized by weight loss in spite of an abnormally voracious appetite; things that look like animate rice escaping from his anus and crawling about on his stool; large, segmented worms squiggling around in his vomit. Nice.) Tapeworms are certainly gross but they can be pretty readily obliterated with medication your vet's got on hand.

Flea Allergy Dermatitis (F.A.D.) is another disgusting thing fleas bring along with them. Fleas bite, the bites itch. Some dogs and even some cats are actually allergic to flea saliva, and so after just one little flea bite, they start to itch and scratch like lunatics. Their hair starts to fall out and a red, sometimes lumpy rash starts to spread. It's a very uncomfortable condition, and the only real fix for it is to get rid of the fleas once and for all.

Hot Spots are another gift that fleas have given us, and our pets. Hot Spots differ from F.A.D. because they don't involve an allergic reaction. If your pet constantly scratches and bites at the flea-infested areas on his body, he can actually end up biting patches of his fur off and chewing through several layers of his skin, exposing a raw, pussy, inflamed and extremely uncomfortable area that is sensitive to the touch. The real bitch of this situation is that the more the affected area burns and itches, the more your critter will pick and bite and scratch at it, which of course makes the condition worse, which makes the scratching worse, et cetera ad nauseum. Desenex Athlete's Foot Powder is really helpful for curing hotspots. It tastes terrible, (evidently,) and it helps to dry out the moist, infected area. Cortisone shots from the vet, antibiotic pills to help prevent systemic infection, and getting completely rid of the fleas are also helpful for treating hotspots.

There are some products on the market that are currently effective in killing fleas and their larvae. Of course, these things might only be good for the next year or two. Frontline and Advantage are topical treatments you use on your pet's skin once a month. There are some oral medications that have good reputations as well, but I haven't tried them on my own critters so I don't know how they compare to the topicals.

Killing adult fleas isn't going to do you any good, really, if that's the only step you take towards flea-eradication in your home. It's better than nothing, but only marginally. Eventually, the eggs that have been laid in your carpet, upholstery, bedding, and other porous places will hatch, those new fleas will breed, and you'll be back at square one within 14 to 21 days. I've been a pet owner and an animal health tech just about forever, and this is the way I like to go about de-fleaing when I need to:
1) Seal up the car, set off a flea bomb in there. Wait several hours.
2) Treat the critters. Bathe them, dip them, use the topical meds, or whatever. But get the adult fleas off of them completely. Use a flea comb to make sure they're all dead and they're all gone. Put critters in the car WITH the a/c on. (I'm sure nobody needs to be reminded that putting your pet in a hot car in the summer is akin to putting him in the microwave, right?)
3) Spray the house. After you've vacuumed, taken down the drapes and the animal bedding and thrown all that in the wash, after you've cleaned the whole entire house really, painfully, Martha-Stewart thoroughly, after you've closed the windows, turned the a/c off, and covered the dishes and food items that aren't put away, use a non-aresol type of spray that contains a growth regulator for fleas. These kinds of insecticides (currently) render the fleas that will come out of the eggs (that you can't really kill effectively) sterile so they won't breed once they hatch. Thoroughly spray all carpets, upholstery, and under things like tables and beds where the mist from your bombs isn't going to reach. (See step 4)
4) Bomb your house. Not in a guerilla warfare kind of way, I mean with flea bombs that again contain a growth-regulating chemical. You need one in every room for sure, and if your rooms are big, use more. Set the bombs off, start them spitting, then get the hell out of dodge.
5) Drive around in your car with your creatures for about 4-6 hours, depending on what the directions on the bombs say. Come home, open the windows, air the joint out and relax. But don't relax a lot, because...
6) If you really want this to work and you're completely serious about it, all of the above should be repeated in 14 days.