The MLBTR current free agent list is out. However, "realistically" the type of players that the Cubs may have a chance of signing is very limited:
Starting Pitchers
Jhoulys Chacin (28)
Ross Detwiler (30)
Marco Estrada (32)
Mike Leake (28)
Tim Lincecum (32)
Kris Medlen (30)
Bud Norris (31)
Ross Ohlendorf (33)
Players with strike-throughs project to long term, big money deals with competitive clubs or too old to spend money to wait three years for the rest of the team to catch up in skill level.
Even then, change of scenery pitchers like Lincecum will probably command much more than the Cubs are willing to offer a failed starter. Second tier guys like Detwiler, Estrada, Leak and Ohlendorf may get short term deals in order to get rotation starts to get to a competitive team by July, 2015 (see, the Feldman-Hammel signings).
But no one on this list appear to be long term solutions for the rebuilding Cubs.