Virtual worlds for do-it-yourselfers:

Metaplace
“Metaplace is a world-creator that runs right in your browser, and that makes it incredibly simple to share objects, characters and entire worlds.”
- Boing Boing

Right now, there are lots of people who want to use virtual worlds for research, or education, or business, but it’s just too darn hard to get one going. Now you can create a world in just a few minutes and start tailoring it to your needs. Basically, we wanted to democratize the process of making online spaces of all sorts…

We speak Web fluently. Every world is a web server, and every object has a URL. You can script an object so that it feeds RSS, XML, or HTML to a browser. This lets you do things like high score tables, objects that email you, player profile pages right on the player — whatever you want. Every object can also browse the Web: a chat bot can chatter headlines from an RSS feed, a newspaper with real headlines can sit on your virtual desk, game data could come from real world data… you get the idea. No more walled garden.

Link.