Firefox nightly builds support WebGL. You can download those here:
However, you need to turn on WebGL manually in the configuration.
about:config in the address bar, then search for "webgl"
and change the value of
WebKit nightly builds support WebGL. You can download those here:
Nightly Chrome builds have support for WebGL, but it needs to be enabled through a command line switch, and also needs the sandbox to be turned off through another command line switch.
Opera does not seem to support WebGL at the moment.