The Hooters promo is a good one. Also right next door at the Tropicana you can get free show tix for signing up as well, along with some bennies. Planet Ho has a $25 table games matchplay and a $25 sports bet matchplay.
The best one, IMO, is Arizona Charlie's Decatur. As of May they still had a $100 slot play rebate promo going for new signups to their players club. Spend $100 in a high-payoff slot, go back to the players club and get a $100 slot credit usable on most of their machines. Play through another $100, and what you're left with is yours to keep.
I plowed mine through the Megabucks machine, I had $80 when I was through, Mrs. Doofus had $230 (and never needed the rebate).