Actually, Brendan seems to have three meanings depending on your source. Many sites and books claim it means 'smelly hair', some say, as this one, that it means 'prince'. However, Bruce Lansky's books claim it means 'little raven'. I'm not sure which is true, I looked it up extensively once and got varied answers. 'Prince' as a meaning is very rare to find, 'little raven' is listed as the most common meaning.
It should be noted, however, that Bruce Lansky is notoriously inaccurate when it comes to meanings and origins (Mackenzie meaning "child of the wise leader", anyone?).