I think this new Jaxer thing just might become the next big new thing for open source web server architectures. It's AJAX all the way, even on the server. DOM on the server!
http://www.aptana.com/jaxer
The more I think about it, the more I can see it competing directly with the well-established open source web server technologies. Javascript is a viable language, and putting Mozilla on the server .. who'da thunk you could build complete client-server apps using only the one language? (Well I guess ASP Classic supported JScript on the server but .. *cough* .. besides, it didn't have HTML DOM running on the server.)
There is huge power in this when you can share APIs across both client and server without any manual proxy or wrapper coding, as this demonstrates:
http://ejohn.org/blog/server-side-javascript-with-jaxer/
I've tried hosting a COM instance of IE on the server in ASP.NET for similar uses but, needless to say, it's not a recommended strategy as it is not scalable on a high-traffic site (uses window handles, takes up a lot of RAM). It's like putting a motor home on a NASCAR race track. Then again, I don't know yet what Mozilla on the server will be like; I'm curious to find out.
I'd love to see something like this ported to ASP.NET.