Virtually All Virtual Worlds

Well, nearly all of them:

What follows is a measurement of comparability with Second Life. By naming these priorities “Onder’s Big Three”, I’m taking ownership of the fact that what follows is purely my opinion. The big three pivotal points of SL-likeness:

1. Real money must move in and out of the “virtual” economy freely. RMT (Real-Money Trading) is designed in, not forbidden by TOS.
2. Users must be able to create unique content and retain ownership over it. Things like scripting and accepting uploads are important here. Multimedia is a bonus. We must be able to control the rights to our content.
3. The world must be persistent, and the users able to change it. Residents like being able to build the world themselves, and don’t need somebody stepping in and erasing their work.

In any case, it's a handy list with some nice videos to give a feel for each world. (Via Raph Koster.)