Leaflet is a nice javascript library for slippy maps, but you still need to bring your own tileserver (OSM is not free to embed for anything beyond light usage I believe)

Yeah, I just had never heard of maplet, so I was unsure if that s/he really meant leaflet or maplet.

Oops. In the process of trying to decide whether to write leaflet or mapbox I confused the names.

I kind of love it :)

Note - I work at Mapbox