[quote name='Over easy']The 3-for-extra $10 trade in deal for EB/GS. It paid for only a couple of my games (FFXII, Trauma Center:SO, and Hotel Dusk), but I'm quite sure it paid off other people's new games/consoles as well.[/QUOTE]
Thirded, or fourthed, whatever - paid for my Wii plus I still have about $400 in credit left for games. The Rhino deal sounded great, but it was too regional. Just about every CAG could take advantage of the EB/GS deal especially if you combined it with various clearances (notably Kmart and Gamerush). I personally used it to transfer nearly $750 in GR credit to EB/GS at a slight profit using crappy clearance games. The GR credit would be sitting there with nothing to spend on right now otherwise (plus they have yet to get a Wii in, so it was definitely a good move back in July-Aug to move that credit).
A close second would be the ongoing Kmart clearance - pretty much they had $1-$8 games of various types all year. Not only did I fill out my collection with plenty of cheap games (Donkey Konga and DK Jungle Beat with bongoes for $5 each, Ape Escape 3 for $4, True Swing Golf for $3.50, etc) it provided trade-in fodder for a number of deals (most notably the EB/GS one but also for the $5 bonus at GR and for regular credit at Gamecrazy).
My third choice would be the 75% off clearance at Blockbuster/Gamerush. There were tons of great deals to be found at Gamerush stores, but even regular Blockbusters had a handful of titles available - things like Soul Calibur II for $5 (new).