No offense, this is kind of delusional. You can't just look at a guy's name and say "Eh, he's not that good, that team's a possibilty." Cassell is not appreciably better (or at all) than guys like Orton, Thigpen, Delhomme. This isn't Madden 08 or Fantasy Football where you just sign any guy who's even a minor upgrade at any position.
At the absolute maximum, there are about 10 teams. If you eliminate the teams with solid but aging QBs (TB, Mia, etc) it's more like 5-6. In reality, I think there will be three teams with serious interest in signing Cassel to be their starter on Day 1: Detroit, STL and San Fran. Maybe Minnesota.