There's a great article by Mike Aamodt in the August Assessment Council News (page 3) on the differences between the mean and the median.
Basic stuff, right? Maybe so, but I'll bet you'll be happy you read through it. I think we all have a tendency (probably because it's so popular) to over-rely on the mean when the median is really what we want. For example, if you're trying to describe the AVERAGE or TYPICAL response, which is better--mean or median? Read the article to find out.