CoasterCD is the name of this new brand-advertising give-away gimmick. It has a 3" CD/DVD attached to the bottom which contains stuff from the advertiser, like promotional videos, songs, screen-savers, whatever.

CoasterCD, Inc. claims they developed these in response to some high demand from beverage companies who wanted some kind of "take-home freebie" that could be easily distributed to bars and restaurants.

But it's clear these can be used for anything. Don't be surprised to find these laying around the sidewalks of Vegas with pr0n on them.