Here is some deals I got from there.
They had a massive birthday sale with lots of deals per day, and a complete GTA pack was going for £5 ($7.50US), when I say complete I mean every single GTA game on the PC.
Then last weekend, got Deus Ex: HR Augmented edition for £6.25 ($9.38), already had DE:HR but a friend didn't so gifted it to him.
Around December got Arkham City for around £8.
Among others, but the best thing is for each purchase you get Blue Coins (BLC) with enough purchases you can easily get a new game for free with them. But you also get Blue Coins for rating a game, reviewing a game if it is accepted (first review gets double), helping someone with a tough problem in the tutor forums gets you 500BLC.
Then when you select a minion type (when first signing up) these things can bring bonuses, Arkham City was £10 but I got for £8 because of a bonus at the time with my little minion. So you keep an eye on him also :P
So its all about community and sharing, and you do get some great deals, so good that they sometimes run out of serials to give to people because of high demand.
Dead Island GOTY is £14.95 on gamersgate
on Steam there is no GOTY yet, but the original with no DLC etc is £19.99
Also Gamersgate does sell Mac games too.
The Anno 2070 pack actually had an incorrect price on it for a while, the pack with the game + all 9 DLCs for 65% off rather than 59% as it is now, so I managed to snag it for the price of just the game alone! Pretty damn slick deal, if you ask me.