While game streaming and cloud gaming aren't exactly brand new, very few companies have tapped into this new technology. However, it looks like big time developer/publisher Square Enix is jumping in with their new service, Core Online.
Core Online is a free-to-play service that lets you play a number of Square Enix titles for free from your browser. Users can find a game to play a choose a level to play from it and either watch an ad, pay $.50 to skip the ad and go onto the next level, or pay for a full game purchase.
The service is just starting but right now you can play Hitman: Blood Money and Mini Ninjas Adventures. However, Square Enix has plans to bring Lara Croft and the Guardian of Light, Tomb Raider Underworld, and Gyromancer to the service.
Source
Core Online Website