When looking over depth charts to prepare for your drafts, it's easy to forget about players who haven't signed yet. In shallow mixed leagues, it's not a big deal, but in single-league universes or deep mixed ones, keep an eye on the following players for your end game:
Pedro Martinez - as of right now the Dodgers are interested. No one knows for sure how much arm he has left, but he looked good in the WBC, and he knows as much about how to pitch as anyone this side of Greg Maddux.
Ivan Rodriguez - even in mixed leagues that require two catchers you could do worse than having one that'll hit for average with a handful of steals and homers. We'd expect him to sign somewhere before too long.
Frank Thomas - he was very good in 2007 before getting hurt last year. Someone could take a chance on him when their DH goes down.
Ray Durham - he's still just 37, and he got on base at a .380 clip last year. He could go 10/10 without hurting your average if he gets the at-bats.
Ben Sheets - he underwent surgery for a torn flexor tendon in his elbow in February. Probably not going to contribute this year, but worth a bid in keeper formats.
Curt Schilling - coming off shoulder surgery in October, says he's interested in signing with the Rays or the Cubs. It turned out that his rotator cuff was in much better shape than expected and was repaired with one stitch. If Carlos Marmol/Kevin Gregg can't handle closing duties, maybe the Cubs would bring in Schilling who would be perfectly suited to that role should his arm prove healthy.
Jim Edmonds - the guy went .256/.369/.568 while playing center field last year. He'll be 39, but he'll still get on base and hit for power if he gets another shot.
Incidentally, while researching some of these players, I came across a Wall Street Journal article by Tim Marchman, arguing that you could build a 59-win team comprised solely of available free agents. (Hat tip: Real GM Baseball.)
Also, I didn't put Barry Bonds on this list because he didn't play last year, and I don't think teams would be willing to take the P.R. hit in this climate by signing him.