WebDev: web based IDE!
I found a really interesting project: a .Net IDE hosted in a web application.
No, I’m not joking, it’s true!! The project is in beta phase and at the moment you can work only on console applications, but what a nice idea!!
You can try it here.
Sharp Reflections 
Just came across your post via google.
Another web-based IDE has now been made available as an open source project. If you are interested in using or developing WWWorkspace, or viewing an improved demo, then please visit:
http://www.willryan.co.uk/WWWorkspace/
Thanks,
Jason Kim (I am one of the new developers)