Allkeyshop has become over the years one of the best, if not the best, site a gamer could ever ask for. It allows user to see game pricing trends as well as the biggest deals of the day and week. Not to mention several free games and promotions for both PC and console.
I especially like the pricing history graph as you can see when a game usually goes in sale and if the current price is close to or a new historically low! This helps a lot during major sales as I can squeeze in a few more games within my purchasing budget.