While it's always been possible to add buttons and other information to Google maps, doing anything complicated has generally required a fair degree of developer nous. Quikmaps (developed by a Canadian now resident in Australia) greatly simplifies the process, allowing easy drawing of straight or freehand lines on any Google map, as well as drag-and-drop buttons and text labels. Registering (a free process that requires nothing more than a user name at this stage) lets you save your doodled maps and generate code to add them to your own site.

Quikmaps