The only promotion running right now at EB is that if you trade-in your games (that are not "POX titles", i.e. games not on the exclusion list) towards select titles, you'll get $10 dollars in store credit towards them (up to 5 titles). Select games for this offer include: Halo 2, GTA: San Andreas, Silent Hill 4, Def Jam Venetta, WWE Smackdown! Vs. Raw, and some others.
So, if you trade in say 5 games towards Halo 2, you'll get $50 dollars.
This offer runs through November 8th.