Over the years, I've tried a great many solutions. My favorite:
1) Office depot rubberbands. About 4 bucks per trillion bands
2) Inkjet perforated cards, 10 to a sheet
3) Hole puncher
I have a LOT of bottles at any given time, so keeping them organized is important. Print out the data (date, gravity, IBUs, style, etc) separate and hole-punch the cards, rubberband through the hole around the bottle neck, done. Takes about 3 seconds per bottle, looks cool.