GameStop's TV ad proudly proclaims that it's the "biggest trade event ever." We can't really disagree. Starting today, GameStop stores will be offering an extra 50% bonus on used game trade-ins, boosting their usually-paltry offerings into the "sort of worth it" zone. Your old copy of Madden 08 won't really help you much in this promo. Instead, look to capitalize on newer game trade-ins. Using the CAG database, we discovered that Modern Warfare 2, New Super Mario Bros. Wii, Dante's Inferno, and BioShock 2 will net about $35 of credit each.
The best bet right now seems to be Mass Effect 2, which will net you a whopping $52 worth of credit (and if you have an Edge card, you'll earn 10% more). Just make sure that, as with many of last year's and this quarter's games, you don't intend to stick around for all that DLC.
As much as you may sympathize with the difficulties publishers face in the used games market, the ongoing 2010 onslaught of games -- including Heavy Rain, Final Fantasy XIII, Battlefield: Bad Company 2, God of War III, Pokemon, and more -- might force your wallet to seek out as much help as it can find.