This is the story of the style I'm creating in TileMill that will eventually be an online transit map for Macon, Georgia's bus system.
Here is a current screenshot from TileMill: 
showing the where the project is at.
The map is also online at: http://tiles.mapbox.com/jllord/map/mta Exciting!
I've made a lovely css/html transit legend but am having trouble getting it to drop in and be read as I intended by mapbox online so it's currently being replaced with an image until I sort that out. The markup for the legend is the repo, photos as well.
The newest of new is the tooltips with a fun bus icon.
In progress/the future: -bus times in the tooltips (when available) -it's own special web site and address searching.
Extra Goodies: The awesome Vallandingham created this gist, using Raphael to create the legend. View it here.
@jllord
jessica@codeforamerica.org @jllord