Besides Acacia, there is SightSound suing CDNOW/BMG over the paid downloades of digital audio/video, and USA Video suing Movielink.com for downloads of video faster than real time.
Burst.com has a patent earlier than everyone, and could be the next Acacia.. they are currently targeting Microsoft.
Another player into this mix is E-Data.... i was going to post about them, but decided this is all too much... we should just focus on one battle at a time against this war on business and patent abuse.
Fight the Patent!