Adam Dunn. Period.
Over the last couple of years, he has been putting up monster numbers up quietly, with an average of about 40HRs and 100RBIs per season. Who wouldn't want him? The Washington Nationals did a good job last year, locking him up for 2 years. This gave the Nats a better finish in the season, instead of a 110 loss season. And there's even talk about contract extensions. This guy can help any team: and he's been overlooked. He'll be noticed when he is with a playoff team or when he hits his 500th HR: maybe even more.