I love this prototype / early version by Mitch Barnett of a web-based IDE for distributed programming using IronPython. It reminds me of my last dot-comet system: a Web-based assessment framework (I'd say "testing framework" but you'd think NUnit when you should be thinking certification). You were presented the pre-conditions, post-conditions, and invariants, pasted your code into the text box, your code was compiled, checked for permissions / size constraints, and then executed in a sandbox that was monitored and constrained in various ways (memory, time, resources, etc.).

What I like about Mitch's idea (other than that beautiful Smalltalk-like browser) is the idea of using this for pair-programming over the Internet. Mitch tells me that's not yet supported, but could easily be hacked.