While a plastic cup might lend itself to a permanent marker label, beer bottles aren't so easily marked up—glass, dark, small labels, not a Sharpie-friendly zone. Rubber bands, however, are down right drink agnostic.
Over at the home-centric blog Re-Nest they had the problem of the lost wine glass licked—as have we here at Lifehacker with LED and transistor wine charms. We've even highlighted how you can use colorful window markers to tag party glassware. Beer bottles, on the other hand, are a bit tougher. At Re-Nest they found a perfect solution, colorful rubber bands. They write:
If you're like us, you have a stash of rubber bands left over from heads of broccoli, bunches of asparagus, and and the newspaper. We're lucky that we have an assortment of colors: pink, blue, green, purple, tan, white. They make perfect beer identification bands, as long as you don't have a huge party (although then you might be serving more than one kind of beer, which also helps). And they're free!
If you don't have the stomach for that much broccoli you could always head over to your local office supple store and buy a big pack of colorful rubber bands. We're fairly confident your beer will be just as happy without the snug embrace of a produce band.
Party Tip: Use Rubber Bands to Mark Your Beer Bottles [Re-Nest]