The browser on the server

I've been wondering about the possibility of running JavaScript outside the browser, in fact as part of the web server. Of course, old-style ASP could be written with that language but that's not really the same - what I want is the ability to take and manipulate objects on the server that you'd otherwise be expected to work with in a browser context. I was thinking initially about JSON - I know that it's perfectly possible to use JSON from other languages (libraries exist for PHP, Python, .Net etc) but wouldn't it be better just to do it with a JavaScript engine? And then I thought, well, Mozilla's engine would be the obvious thing, I presume they've built it in such a way it can run in other contexts. So I started googling and obviously this is a very well-trodden trail that I'm just late in exploring: there's loads of stuff out there. I've not checked out any of it properly but thought I'd put some links here in case anyone else is toying with the same idea, or is prompted to now.

Incidentally, one of the things that's nice about JavaScript is that it's all focussed around the DOM, unlike many other languages, and I'd think it's pretty forgiving too (depending on the engine). All of which makes it a good candidate for screen scraping. And one thing I've not yet found is a way to tie this into .Net nicely

• http://en.wikipedia.org/wiki/Server-side_JavaScript This lists loads of products for various environments that will run JS server-side. Looks like Mozilla's Rhino and SpiderMonkey products are the basis for most of them.
• http://ejohn.org/blog/server-side-javascript-with-jaxer/. This must be the first stop for me. How cool is that? Here's jaxer itself: http://www.aptana.com/jaxer/. Yes, it is based on Mozilla. Damn, it's for Apache, but it's not a deal-breaker.
• from the same source but older: http://ejohn.org/blog/bringing-the-browser-to-the-server/ Look in the comments too, plenty of starting points there
• I also turned up some of what I take to be the original Netscape JavaScript documentation, which talks a lot about server-side javascript but in relation to the old Netscape Enterprise Server