OK, internet people, here's a challenge.
I want a way to attach arbitrary text tags to songs in my music library, and then retrieve all songs with a particular tag. Either simple one-word/string tags in the way that del.icio.us and flickr work, or more complex name-value pairs, as long as the name-value pairs are not required to have a unique-key name. For example, instrument:trumpets and instrument:banjo.
Unfortunately "tagging" with respect to .mp3s has the common connotation of populating the ID3 tags such as Artist, Genre, etc., and that's not what I'm talking about (although I would also want a way to auto-tag songs in my tagging scheme based on the information held in ID3 tags). This makes searching the internet for this capability quite difficult.
Last.fm does part of this, and would theoretically allow me to arbitrarily tag songs, but that information isn't integrated back into a music player/playlist editor to allow me to quickly find or play songs by tag, unless I want to use last.fm's limited internet-based player, which I do not. On the other hand, they do have the capability to tell me how other people have tagged a song, making it potentially useful as a way of harnessing aggregate social data to make tagging easier.
The ideal software would be a plug-in to either iTunes or winamp, as those are my favored music players.
Suggestions? Ideas? Questions?
3 days ago