AOL and Tax Resolution have dropped Limbaugh today. And I'm told Peter Gabriel has asked Limbaugh to stop playing Sledgehammer as rejoin music on the show. Perhaps that's another angle -- I know Limbaugh plays Rush (the band) as rejoin music. I'm sure they wouldn't mind having their music pulled as well.
ThinkProgress has identified two more advertisers. Lifelock and Lear Capital. Also, here's a master list for your records.