Thanks to Mark and Gaurav, we have now a nice list of free games download sites. Most of the games you will find are a mix of playing online for free and if you want to download and play them, you have to pay. Because I am mostly playing puzzle games, which I do not need offline, I play the games online for an hour or two and then I forget about them!
Take a look at the list here: Games List
If you have more URL's for us, please report them on the homepage of tradebit!