Farrar Hudkins wrote:

> I think the purpose is for us to see what the others are listening to.

The grouped charts can be quite interesting, I think.  You can see what 
individuals are listening to, but it also works it out by the group. 
For example;
http://www.last.fm/group/Extensive+Musical+Taste/charts

If there's a large take-up, it might be interested to look at the charts 
a few months down the line, to see what have been the most listened to 
artists and tracks.

Or you might find that a bit too anally retentive.  And that'd be fair 
comment, perhaps.