I collect live recordings, so there's a bunch of less common stuff I use a good bit: Date performed, handle of who recorded it, tour, a personal rating system for the recording quality, additional artists (special guests + the like), and general comments I might want attached to the file. ("clips at 0:40" or "heckler in the quiet part"). I may have 20 copies of the same song, and I may even have multiple recordings of the same song on the same night from different people.

At least for some artists, there's a huge number of show recordings out there. The guy who maintains the (unofficial, although known and tolerated by the artist) live archive for Nine Inch Nails is up to >1,000 recordings, for example.