New map styles from Stamen Design
I learnt today that Stamen Design have released new map styles for Open Street Map data. I really like the watercolor one, as it is quite different from what is usually seen on web maps.
The other two are:
A Javascript API is provided in order to access the tiles. If you would like to roll your own maps (with TileMill, for example), the styling instructions are also available for Toner and Terrain.