If healthy I'll go with the Wade Miller bandwagon. After a mostly injured 1st half in 2002, Miller's 2nd half #'s were stellar. His splits were nowhere near as impressive last year, but still a vast 2nd half improvement.
Jose Contreras is a low risk investment.
Kris Benson's has been improveing as of late, and I dont think his statline will improve. A trade to a contender could improve his 2nd hald trade value to owners that dont see pst wins however.
Brian Lawrence noticeably improved his ERA after last years break, which coincides with the season he is haveing.
"Son we would like to keep you around here but were trying to win a pennant this year."