American Atheists has probably filed more lawsuits against individual atheists and other atheist organizations than any religious organization ever has. Usually these lawsuits are intended to harass people who were once members but have fallen out of favor. I know dozens of people who have had this happen to them.
Well, I don't know how much background you have on American Atheists, so I'll give some general examples and a few specific examples.
In many of American Atheists monthly mailings to members there were accounts of ex-employees & members who allegedly did horrible things to sabotage the organization (usually this was just a personality clash with Madalyn or Jon Murray and not much else). But their standard claim was that some damage had been done and usually they claimed that their "mailing list" had been stolen. Many of these people then had lawsuits filed against them for the alleged damages. This pattern was repeated over the years with many ex-employees or ex-members who had some official rank in the organization (usually chapter officers). During the late 1980's it became a bit of a joke to see how long it would be before the latest new secretary or clerical help would turn out to be a "closet Christian" (or something worse) who had just been fired before they had a chance to ruin the organization. For a long time the people I knew in Houston took a lot of these claims at face value even though they often knew the people in Austin who were involved and couldn't understand why they had suddenly become "traitors".
One fellow (John Woodward?) who is the editor of a publication called "The Match" (which used to be advertised by American Atheists) had a falling out with the Murray-O'Hair's and wrote a booklet "The Mouth That Roared" on his experiences with the Tucson chapter of AA and all the accusations hurled against him. His account fit the pattern of other people who had been drummed out of the corps. And also fit what was soon to happen to some of my friends in Houston.
Around 1991, the story hit a little closer to home when AA folded several of its chapters and filed lawsuits against some of their ex-chapter officers. In Houston (where I live) AA filed a lawsuit against 4 or 5 ex-officers claiming that they had also "stolen" the AA mailing list (among other things) and sued for $100000 in damages. Nothing EVER came of this lawsuit. It was apparently filed (for about $50) in Houston to harass them and screw up their credit ratings, etc. (I know the people named in the lawsuit and the details of what happened and I know that the lawsuit is totally unfounded.)
Another thing AA tried to do was get a local Pacifica Radio station, KPFT, to hand over control of an atheist radio program to American Atheists. AA claimed that the program was "rightfully theirs" and should be turned over to Don Sanders (head of American Gay Atheists and national AA officer) to continue programming. KPFT replied that they had no such agreement with AA and that the radio program was strictly between the station and the ONE person who had agreed be the director of the show. There had NEVER been an agreement giving AA control of the program. AA continued to harass KPFT with letters, but eventually gave up because they had nothing to stand on. This whole episode showed just how nutty AA had become and was typical of the silly lawsuits they filed just to harass and bully people into doing what they wanted. A lot of naive people just cave in to this kind of pressure and do exactly what they ask. Unfortunately for them, we knew their techniques pretty well and just waited it out.
A lot of the atheist organizations you see in the U.S. were formed from folks who fell out of favor with AA and were kicked out of the organization. Often this was done with a lawsuit hot on their tails which almost never amounted to anything. The Freedom From Religion Foundation was started in a similar move as a chapter which was kicked out of AA. The same is true of Atheists United. Atheist Coalition was also formed by a fellow I knew in Houston who was kicked out during one of the AA annual conventions. Nearly all of these people were once near the "center of power" in AA or were recognized for their outstanding work by AA at one time in their past, so they are not lowlife or anything. One year you can win an award at the AA annual convention and the next you can be named in a lawsuit and be drummed out of the organization.
AA has the idea that they can sue nearly anyone for anything and get away with it. They think that the average individual atheist cannot defend themselves against their organization and they also know that the smaller atheist organizations do not have much money. I think FFRF could probably kick their asses, but I doubt that they get much grief from AA nowadays. I also think that the groups under Atheist Alliance could now probably fend off a direct attack from AA, but I wouldn't bet the farm on it.
One of AA's techniques for growth is to try to absorb the funds of other organizations through lawsuits. It is a bit like winning the lottery if they are successful, so it is worth the risks. I am pretty sure this is what their fight with the Truth Seeker organization is all about. It's probably appropriate that they are getting sued for racketeering. If the people who are suing AA for racketeering were to get serious about it, I am sure they could find many other people who could provide examples of how AA runs their business. AA has made as many enemies among the atheists as they have among the religious and as far as I'm concerned, it's just a matter of time before they take a well-deserved hard fall. I am going to check through the atheist grapevine in San Diego to see if anyone else knows what is going on with this lawsuit. Who knows, we might be able to find a few others willing to join in the fray.
As for my personal situation, I guess I could catch some shit from them (or some rabid AA member) for telling some of this stuff, but I'm not as poor as some of the other individual atheists they try to push around. I also know plenty of folks who know where other skeletons are hidden who just might come to my aid in a serious fight.