While I'm not sure about the suits by concert managers or promoters, I believe he is also being sued by Sotheby's for failing to pay up items he bid on at auction, or something of that nature. I could
look it up for a link, but I find other topics more deserving of such research. I'm sure ET or FOX will give us plenty more coverage in the weeks to come.
And, as Jaime pointed out, he's also attempting to sue Sony. While it may be listed as a suit for "breach of contract," my understanding is that he's accusing Sony of failing to properly promote the album because they were racist. I hope I'm never so pathetic and desperate as to place failures and shortcomings so clearly my own onto the backs of others.