I keep every band in a book with a simple rating system (poor, good, v good, excellent & heaven). Every time I see a band it seems to bring back the taste memory fairy........
I never used to keep my bands. For some reason though, I have recently taken keeping bands from most of what I smoke. If for no other reason, just to have one from every marque.
I have an empty box that I throw all of my bands into. I started out just collecting 1 band from each type of cigar I've smoked (no duplicates) but recently I've taken to collecting all of them for a future project.