A community website dedicated to expatriates: Spanish people living abroad. Their map is interesting, and it seems that many users are connecting to this new venture. A good way to interact.
Another community that invites members to map themselves: Basque blog community blogari.net displays a couple of maps in their homepage with the location of the active bloggers that take part (look in the bottom right column).
Campinguia.com has created Google Maps for their camping-site review website. One map per Spanish province. Barcelona Point is a real estate website that shows some apartments available on Barcelona. Interesting spots of the city also mapped.
Fuerteventura 3D is a website that displays different kinds of views about that island in
the Canaries. Besides their own maps, they display satellite imagery integrating Google Maps.