tmpltr
tmpltr is a jsFiddle clone with almost none of the features, + mustache templating.
http://rocktronica.github.com/tmpltr/
All JavaScript. Should run fine on all decent browsers. If you fork it or run it somewhere else, do me a favor and comment out analytics.js so you don't skew my pitiful numbers.
Made by Tommy (@rocktronica). MIT licensed or as components require.