Robin Good: Build-a-Map is a web app which allows you to build custom maps and itineraries by adding visual information layers on top of Google Maps.
Differently than creating a map in Google Maps by using the "My Places" feature where you can only add placemarks, paths, and shaded shapes, Build-a-Map allows you to add directly your own data sets, special shapes and custom labels.
Free and paid versions available: http://www.buildamap.com/plans-pricing.html
Find out more: http://www.buildamap.com/
Via Robin Good