To demonstrate the use of OpenStreetMaps on an own map server, we built a presentation using the brand-new Leaflet library from CloudMade. It is backed by a huge server-side tile cache and has been optimized for the fast display of maps on the Web.
The server is not yet fully ported to Node.js. Some parts currently rely on NGinx which has also a superb performance on static content like the map tiles, but that will also be a perfect job for Node.js. Stay tuned.
The maps can be embedded in HTML pages and additional layers can display markers, popups, polylines, polygons, circles and images. See the Leaflet documentation for full details.