From Bill Williamson of ESPN (not a rumor, per se, but from Insider):
Buffalo has quite a bit of money to spend in free agency and few of its own players should be top priorities, with the exception of franchised safety Jairus Byrd and guard Andy Levitre, who should be the most sought-after free agent at his position. Bringing Levitre back should be a focus, and Buffalo could use more pieces on defense, but the Bills really need to add offensive weapons (especially if they plan to select a quarterback early in the 2013 draft). There are a lot of tight ends on the market and in the upcoming draft class, but free-agent wideout Greg Jennings would be my No. 1 target. Jennings is an established receiver who could legitimize the passing attack. The presence of Jennings would also allow Steve Johnson to see more favorable coverage matchups.