Evil Brain Jono's Natural Log
http://www.evilbrainjono.net/cgi-bin/blog/showblog.cgi?permalink=498
"Atul has written an awesome thing! It's a Javascript wrapper for the Z-machine -- the engine behind all the Infocom text-adventure games."
Parchment
http://parchment.toolness.com
"Below is a list of z-code based interactive fiction titles made available by The Interactive Fiction Archive. You can click on an entry to start playing it."