Westboro Baptist Church is not affiliated, as far as I know, with any type of Baptist church, Southern Baptist or otherwise. I'll expand upon this later in this writeup.
Aside from opponents and others listed in the aforementioned writeups, Fred Phelps also employs the detestable practice of picketing funerals. He's picketed the funerals of AIDS victims, those who worked for gay rights, politicians and the families of politicians (He picketed the funeral of Bill Clinton's mother) and gained national media attention by picketing the funeral of Matthew Shepard, who was beaten and left for dead because he was gay.
On a side note, Matthew Shepard eventually died of his injuries after days on life support. A bit of bitter irony here is that while Shepard had nobody to protect his life when it was in danger, Fred Phelps and his cult of hate had a barricade as well as police protection so that he could spread his message of hate without harm coming to him or his followers.
As well as picketing the funeral of Matthew Shepard, Phelps maintains "a Gospel memorial to poor Matthew Shepard" at http://www.godhatesfags.com/memorial.html which includes:
On the death of Matthew Shepard and the Westboro Baptist Church picket of Shepard's funeral, Phelps has this to say on the "memorial" page listed above:
When Matthew Shepard died on October 12, 1998, every pervert in this country (from Bill Clinton on down) used his death as a soap box to promote so-called "gay rights." In religious protest of this, WBC picketed the funeral of Matthew Shepard, to inject a little truth and sanity into the irrational orgy of lies consuming this world.
Thanks to Wharfinger for poiting out to me that truly warped bit of irony. Quoth the Wharfinger: "Sanity? SANITY?!"
As for his picketing of churches, I've seen his group picket a church once, though Fred Phelps himself was conspicuous in his absence. This was the picket of the Lord of Life Lutheran Church in Ames, Iowa. He was picketing because Rev. Steve Sabin was homosexual, and the Southeastern Iowa Synod of the Evangelical Lutheran Church in America (ELCA) was considering action against Rev. Steve Sabin and the Lord of Life Lutheran Church because of Steve Sabin's homosexual relationship with Karl von Uhl. A minister of a Baptist Church in Ames (I don't recall the affiliation, but I know it was a mainstream Baptist church, unlike the Westboro Baptist Church) wrote a letter to Fred Phelps stating that while he agreed that homosexuality was a sin, he did not think the actions of Phelps were in "the spirit of Christ". Phelps didn't hesitate to then call this conservative preacher a "sodomite".
The following are a few examples of the signs that Phelps and the Westboro Baptist Church uses in its pickets (some of them seen in the photo at http://www.godhatesfags.com/images/acf.jpg):
Westboro Baptist Church also picketed Iowa State University, alleging that ISU was made up of "fags" and "sodomites," particularly because of its on-campus Gay and Lesbian group.
Incidentally, Fred Phelps uses the labels "fag" and "sodomite" interchangeably for pretty much anyone who doesn't agree with him wholeheartedly.
For some of the details about the Iowa Synod, the ELCA, and the proceedings, I used the following website:
http://www.execpc.com/~deaven/Opinions/proof.html