Card punch emulator
Fun little punch card generator site -- makes an image of a punch card.
IDE for Interlisp and Common Lisp
Online IDE for Interlisp (and Common Lisp).
CloudpilotEmu: A PalmOS emulator for the web
A PalmOS emulator that can run in the browser; could be interesting if I ever want to try and play with any of my old Palm code again.
Build your own NeXT with a virtual machine
Instructions on getting a NeXT machine up and running in a VM.
Web WinAmp
Webamp, it really whips the llama's ass!