Here are some of the names that caught my eye.
Hartwig, C, Pittsburg - He is a two year starter (31 yrs old) that got bounced by Pouncey. He's 315, so perhaps he could be a G/C type that could eventually bump Holland off the roster. Would be nice to have someone who could play G or C, push Gurode and Davis and buy us some time for the young guys to mature. He wouldn't be cheap as he can probably start for a lot of teams.
Fenuki Tupou, G, Philadelphia - He was a rookie last year and I remember liking him coming out of college. He's a big, athletic guy but is raw. Perhaps Hud can do something with him.
Sean Ryan, TE, Tennessee - We drafted him 6 years ago, and if I remember right, wanted to keep him (or bring him back?) but something happened. Seems like a good fit for what we're missing, a blocking TE.
James Hardy, WR, Buffalo - The only reason I mention him is that I remember the Cowboys liked him a lot in the draft. This is only his 3rd year in the league, so perhaps moving from the wasteland that is Buffalo will change his trajectory. I can't see him bumping Hurd though, since I doubt a 6'6" dude can play special teams well.
Anyone see anything else? Hartwig seems the most intriguing, although I'd think he'd have a better opportunity than as a backup.