This is pretty cool. You upload your XML file to this site (you can zip it first) and once you upload it it takes the data and creates a number of different graphs and other visual representations of all of your song info. And no there isn't any harm in sending this data, your XML file is in your iTunes music folder and contains the stats behind play count, date added, etc.
www.itunesregistry.com
www.itunesregistry.com