hey Zeb....I don't know what client your using....In apex you can search according to file type,I don't know if that would help in your case or now.....for instance in our hub we share only lossless music, such as .flac and.shn, .ape ...........so if I wanted to check and see if there are any .mp3's floating around all I do is type that in the client search box and see what I come up with.
It would be real cool if we could write something like in the hub though, such as a inform pm or something.