Edit: It's up at http://github.com/daeken/Dyna6502Asm now. If someone could actually host it so that people can test it out, I'd greatly appreciate it. I'm writing up a small document on how it works, for those who are curious; it'll be in the repo in a few minutes. Oh, and I believe that this was the first dynarec'd emulator for Javascript; this was back in December 2008.

Edit #2: Strategy document is up, here: http://github.com/daeken/Dyna6502Asm/blob/master/strategy.md. The same exact mechanisms should work just fine with this emulator, if someone is so inclined. One thing you ought to do, though, that I never got around to, is adding a simple checksum to the code cache. When you attempt to execute a block, check to make sure that the code in memory is the same as the one in the code cache; if it's different, then the code has been modified and needs to be recompiled.

Edit #3: Thanks to icefox, I now know how to host on github! http://daeken.github.com/Dyna6502Asm/