Draft Tek is the internet website that runs computer generated mocks. I think this one is pretty interesting.
They have Buffalo getting Riley Reiff in the first round, Ryan Tannehil in the second, Brandon Jenkins in the third, Kheeston Randall (DT/DE from Texas) and Tavarres King (WR from Georgia) in the 4th, and Cliff Harris (CB from Oregon) in the fifth. I know Jenkins has been projected to the Bills in the first round in a number of mocks.
Overall, this mock does a good job of meeting needs for the Bills, and most of these guys have good upside. Cliff Harris has character issues or he would likely go a couple rounds earlier at least. I know one other CB in the draft with character issues is Janoris Jenkins and quite a few mocks still have him going in the first. Harris is not a big CB (5'11") but his skills are excellent.
http://www.drafttek.com/CMDRound1.asp