AjaxVTT is a "Virtual Table Top" utility for multi-user, web-based battle mapping. It lets you play table-top RPGs (Role Playing Games) over the Internet. It is built in PHP and outputs standards-compliant dynamic HTML, CSS, and Javascript (using Ajax), so the only things you need to play are a web browser and a high-speed/broadband Internet connection.

This is a demo site. All games, characters, and user accounts are regularly purged. There are, however, test accounts.

Test accounts:
test1/test (GM rights)
test2/test (player)
test3/test (player)

Note: Remember this thing is an alpha. You'll have the most luck using Mozilla or something based on the Gecko engine (Firefox, Camino, Galeon, etc...).
Opera and Konqueror do work, except for logging-in (if you create a new account you bypass the login process).
God help you if you're using IE.