GISCloud.com. CartoDB. CartoDB + Leaflet = Easy. One of the biggest sources of buzz at FOSS4G was CartoDB.
It is a hosted solution from Vizzuality that uses PostGIS to allow you to store your spatial data online. I got a beta account a couple of weeks ago but life (i.e. paying work) kept getting in the way but I finally got to play with it recently. MapMint. Mango Map. GeoIQ. TargetMap - Create & share customized data maps on Googlemaps. Free Online Mapping tool. Home - mapbiquity. ArcGIS Online. ArcGIS Explorer Online.