It isn't often that salary dumps take on the massive scale that I am about to propose, but it isn't often that outrageous contracts accumulate in major league teams the way they have with the 2010 New York Mets. So here is my proposition:
Consider the case of the Red Sox. They could definitely use an upgrade in their outfield production, and Jason Bay even now would be very much an upgrade over what they have. Furthermore, there is value to be added in moving Jason Bay back to the Sox, as his success there in prior years would make him better candidate for a rebound there than here. Thus, Bay is (marginally) worth more to the Sox than the Mets.
Castillo and Ollie only have one year left on their contracts, so it is not impossible to move them in a salary dump if the price is right. Combined, it amounts to $54 million for three years of Jason Bay (since Perez and Castillo as players are dead-weight). Bay is 32 and will be coming off a 1.8-ish WAR season (roughly 7 million in value) but has averaged 3.7 wins per 700 plate appearances in his career. Averages actually mean very little with Bay, as he has been wildly inconsistent throughout his career, posting three full season WARs over 5 (peaking at 5.6) and three at or below 2.9 (with an atrocious -0.7 in 2007) which also indicates a significant probability of rebounding later in his career. Assuming a regular decline from age, we can justifiably posit an average yearly WAR of 3.0 going forward for the next three years. That, at $4 million per win, gives you $36 million, leaving $18 million surplus that the Mets need to make up. In reality, the Sox would demand that the Mets make up, say, $22 million, since it would take more than a retail-priced free agent for the Sox to bite.
What's intriguing is that should the Mets assume $12 million of the contract at $4 million per year, they only need to give an additional $10 million of value from their farm. A controlled Ruben Tejada combined with a lower-yield guy (Lutz? Welch? Both?) would be able to compel the Sox to yield a sleeper prospect in return (and I trust Omar with evaluating sleeper prospects). Or if you wish, you could pay out $7.3 million per year and even out the trade with a Chris Carter-type non-prospect in return, and not give anything up.
The Sox would improve their outfield situation at subsidized cost. The Mets would free up their payroll by $32-$40 million, depending on how much they want to give up and go after Carl Crawford and try to do better going forward getting value for their money. The same scenario would apply to any other team with a budget who needs an outfield upgrade. Feel free to make a suggestions, or excoriate the whole idea if you like.