The player who is most likely to bring back more than he is worth might be Avery Bradley.
The expiring contracts of O'Neal, Garnett, and Allen are difficult because teams that trade for them usually want to dump longer contracts. If you were going to blow up the team and trade KG, is there any player you want that another team wants to be rid of who is signed to a similar sized contract that goes beyond 2012? Jermaine O'Neal makes less so is probably easier to trade. Plus, there are always teams looking to shore up their big man rotation. I am not sure if I would trade him for someone signed to a full MLE mistake contract and a first round pick from a playoff team, but that is what he might be able to bring in.