If you are looking for a bus around Rennes or from Dinard to Rennes, try this link here. It is even in English.
I use the bus to get to Rennes station when I travel by train.
The bus actually takes you to the station (about 50 m from the front door!).
It is only 2.50 euros per person for the trip (1 hour long). Not bad!
Does anyone have a link to a good bus timetable website for Brittany? If so, please post it here.