Has anyone done any experiements with node.js and Jägermonkey? They’re getting pretty close to V8 in speed ( http://arewefastyet.com/ ) and might prove better for server use (utter conjecture on my part).
* whitebeam http://whitebeam.org/, which to my surprise appears to be not actually dead yet.
* jaxer http://jaxer.org/
* couchdb
But none of these seem to be low level enough to make a reasonable comparison.
Flusspferd http://flusspferd.org/ seems most like node, but using spidermonkey (circa Firefox 3.5, it seems, but actively maintained, so there's hope for future enhancements). Unfortunately, it doesn't yet seem to have all the handy web serving stuff that node has, so probably still not useful for a competitive benchmark.
It would be a lot of work to abstract the js core.