The Mets have signed several veteran relievers to minor league deals in the last several weeks, but the chatter in the Adam Rubin Lobby seems to be that they aren't done shopping for relievers. According to Rubin, the Mets have definitely got Jose Valverde "on their radar", while they also have some degree of interest in a reunion with Francisco Rodriguez.
Rubin also reports that the Mets were indeed in contact with Roy Oswalt over the winter about joining the Mets, although it sounds as if they wanted him to sign as competition for their closer role as opposed to fighting for a spot in the starting rotation. Oswalt reportedly has little interest in closing, and therefore isn't really a fit for the Mets.
The report mentions Brian Wilson, whom Mets scouts watched throw at UCLA last month. His velocity is still low, and apparently the Mets don't feel he's ready to help the big league team.
Rubin says that the Mets have one "serious offer" on the table for a non-closing late inning reliever, and he speculates about Brandon Lyon and Kevin Gregg. In the middles of January Chris McShane took a look at some available relievers, and had several other guys in his article that could fit this bill as will.
The article concluded with Rubin telling us that the Mets still expect more additions to the bullpen before pitchers and catchers report in 10 days.