My girls have been playing on Zoodles and they really like it. Here's my review of it.
It pulls games from a wide variety of sites, so I don't have to search for games. It finds them!
Each kid gets their own account and it customizes the games according to her age.
It opens up in a window that takes up the whole screen, so that is the only thing the kids can click on. This is great, because they can't accidentally go to any other websites or mess up any settings.
Along those same lines, once they choose a game, even though it's on an external website, they can only play THAT game. If they want another game they go back to zoodles and pick from the list of games.
Some things that I find to be useless (and maybe even harmful for a parent trying to deschool) is the emphasis on dividing the games into subjects. It creates reports for the parents showing what skills or subjects the child has been learning according to the games they are playing. The parent also has the option to promote certain subjects, so if you think your child isn't playing enough math games, you can make those the only games they see. This is the part they charge for, however. The membership also includes more games and stories, which might make it worth it if my kids get bored of the games and stories available on the free version.
All in all, it's a great site that I wanted to pass on! But if you are new to unschooling, and really excited about the educational controls on it, please read here and let your child play the games she wants just for fun.