SS Alex Rodriguez is probably the top available player. But it'll be slim pickings for him. The deal would have to include a young, top of the rotation kind of guy.
Pretty much everyone on the roster is available besides the following:
1) 3B Aramis Ramirez
2) CF Vernon Wells
3) RF Fernando Velazquez
4) SP Celes Sanchez
5) SP Harris Claiborne
6) MR Jeff Zimmerman
PM is preferred