On the same line of thought, we're working on http://www.erbix.com which provides Server-side JavaScript hosting (and a browser-based code editor) using the open-source Rhino engine.

To help SSJS in getting main-stream adoption, we've coded some apps, Erbix Forms and Erbix Blog, written completely in JS, which we've open sourced and launched in the Erbix App Store ( https://secure.erbix.com/marketplace ).

If you have any feedback let us know.

Duostack has also a nodejs setup.

I have been working on a small game and so far I am very happy with how it works.

http://www.duostack.com

My company Nodejitsu (http://nodejitsu.com) also provides a node.js Cloud Platform-as-a-Service.

I'm the author of forever and node-http-proxy and it's good to see our production quality node.js software being used by other people :-)

There's also http://webbynode.com/

They have ready-made stacks with Node.js, Rails and Django.

Joyent employs ryah. They've been around for 6 years, although I'm not sure how long they've been doing server-side JS (at least since they bought Reasonably Smart at the start of 2009).

I would definitely be inclined to go with the Joyent service since that's where Ryan Dahl (creator of node) works. And Heroku pretty much rules this realm.

But competitors are good!!

And http://www.akshell.com/

Just to add to the list, there's also nodeJsCloud: http://www.nodejscloud.com/

Thanks to everyone providing the links to all these services. I knew of some of them, but not others. Thanks!

To complete the list: http://apps.jgate.de It is based on AppJet and CouchDB.