There was an article in the Washington Post about this not too long ago. It said that teachers tend to expect less of students that have "trendy" names and strange spellings (like Brytni or something to that effect). I can't find the article right now but I think it said something like it gives the perception of lesser educated parents, and so they expect the student to be less intelligent and not have as much support at home. I'm going to see if I can find it, but I think it was about a month back, so it's buried on their site.
ETA: The
Baby Name Wizard is neat too, it's a javascript graph that tells you how popular names are, dating back to the 1900s. So if you put in Madison, you can see that there's a HUGE spike in the early 1980s, right after "Splash" came out.