There is also https://compilify.net/ and http://executify.com/. But it's always good to have more options.

compilify seems to take a long time to compile code :(

It is open source though.

There's also https://jitjot.net

The blog entry explaining how to use it is here: http://sbknull.blogspot.com

It's built on ASP.net MVC. We're thinking of open sourcing it.

It saves a new version of your code with each save and you have a repository of code entries via your user link:

https://jitjot.net/u/acoma https://jitjot.net/u/mlatham

Of course you can just park code there if you'd like.

We do something similar at http://runnable.com/.NET We run mono however on the back-end

Huh, first time I've seen this one, very interesting. Any idea what kind of volume they handle and whether or not they're profitable?

I doubt they're profitable (yet), they have only started playing with business models recently.

But the same platform has been used to run spoj.pl, a rather popular programming contest site, for many years.

Also http://www.coderun.com/ide/