Is there a lyrics component for foobar2000 that will download lyrics for songs (based on filename or tag data or whatever) and then write it to tags, and then display lyrics for the song from tags if you want? Or, is there a plugin that'll download lyrics and write them to tags for, say, MediaMonkey, and then a plugin for foobar2000 that will display them?

No plugin to download. You may be able to find an external program to put the lyrics in the tags, then you could use trackinfo to display the lyrics, but its not a very elegant solution. If you are already using trackinfo for something, you can copy the trackinfo dll and rename it to somehting like foo_uie_trackinfo2.dll and have a second trackinfo config.

Ok, thanks, I'll see what I can find. Anyway, it might be a cool component for somebody to make, if anybody has the talent & interest.

try that: http://www.mirkforce.net/lyricsdb/

Maybe it's that what you was searching for: Lyrics Panel

looks good to me! I'll check it out and follow its development!