Josh Willingham is my favorite pick. Last year of his contract, $7 million due in 2014. Career .833 OPS career, generally a 20-30 HR guy. Playing on a last place team that has been in last place for years. He's a hack defensively, but in LF at Fenway with an otherwise excellent OF, he'll be fine. With the Twins continuing to be desperate for pitching, I bet you could get him for Felix Doubront.
I have a few other ideas. Michael Cuddyer is owed 8 figures on the last year of a contract for a bad team. If he can recover from the injury before the deadline and show he is healthy, he would fit.
Matt Holliday is owed a lot of money, and could be available if the Cardinals fall a bit in the standings. The World Series loss hurts the trade a bit, but Card fans won't have to see his bat against them.
Denorfia is a bit better defensively and worse offensively, but he is a good player on a bad team.
Seth Smith would be a great platoon option for Gomes.
The Rangers have good expensive outfielders and are in the middle of a record-breakingly unlucky season.