GameStop is one of those retail locations you'd love to hate. You can head to the store and get berated for not following their wacky pre-order methods (which was probably derived from ancient Cultist rituals). Despite their many cons and kinks, GameStop is still one of the largest retailer dedicated to gaming in the US, so they'll often have some pretty decent pre-order bonus/specials. This practice however is becoming more and more less exclusive as retailers such as Amazon and Best Buy get into the game of bonuses and discounts.
You'll find the occasional GameStop coupons and discount posted above on Dealzon's page, and we'll often cite the rather nice Buy X game and you'll get X amount of free game deals via Gamestop. As any brick-and-mortar customers of theirs know, you can often find a good range of used or Buy 2-get-1-free offers at the local store fronts. Personally, as long as they dont start pitching "extended warranties" for games they sell, GameStop can still be a decent place for large inventory of gaming goodness.