over at
www.gog.com . All you need to do is create an account and add it to your gameslist (from which I suppose it won't vanish again), which will already include
- Beneath a Steel Sky
- Dragonsphere
- Lure of the Temptress
- Teen Agent
- Treasure Adventure Game
- Tyrian 2000
- Ultima IV Quest of the Avatar
The site seems a lot like Steam minus a client software and only offering games that are DRM-free. Though there are only 374 games listed, it might be worth a look if you're into older games, because that's mostly what they offer (alongside some contemporary indie games like Alien Breed, Darwinia and Space Chem), though they also have a few newer blockbuster ones like Assassin's Creed and Trine. There's some sales going on just like on Steam and if you're interested in buying something you can do that via credit card or PayPal. It seems most games also include a manual, the soundtrack and artwork which you can download seperately. Have fun.