Colleges and universities don't just provide educations, they can form their own communities that tend to be liberal (or at least more liberal than the surroundings--unless we're talking about Bob Jones U.) and in some famous (and infamous) cases such as Silicon valley, form the nucleus of whole industries. They can be safe havens in otherwise conservative areas or beacons of light when one feels ignorance and darkness pressing in.
Oh, and there are always young people about, and often cheap beer, which can be cool or annoying, depending on one's predelictions.
A while ago emptywheel asked about college towns and the discussion of liberal radio also brought up the idea that broadcasts should be available in college towns--so let's see who the college townies are.
Note, to qualify as a "college town", the place has to be associated with one (or possibly more) college or university which is the focal point for the community and one of its top employers. In fact, in the most typical cases, the town is practically synonymous with the school (Ann Arbor, Palo Alto) or has the same name as the school (Swarthmore, Princeton).
I realize that there are cities with many major universities associated with them. They get their own category--they are not college towns.
If you feel like it--give a shout out to your town in the comments.