Mooix is a MOO that is implemented on top of unix and which can be programmed online in any language. Its website is http://mooix.net/.

I'm not currently using or developing mooix; a few other people make commits from time to time. I have some grandiose plans for the next generation of mooix, which I might get around to fleshing out some day.

Some thoughts on mooix in my blog.