For my tiny blog (engine) based on node, express/connect and mongojs I needed a simple rss feed solution. I discovered and decided to go with the nice working npm module node-rss instead of writing xml myself.
What this code example does
Basically I create an get event on route
/feed/rss, generate a node-rss object initialized with base values and add item elements to it while looping over a mongojs collection result array (holding my post items to be reflected). Finally I send a response with an appropriate content type header. My example is directly bound to an express get event callback for a simple static request path, but you may of course move it to route exports or whatever.
No big deal, but you might find this portion of code useful as a starting point when seeking for rss solutions.