New past-time for technogeek audiophiles: "burning circles"
The ubiquity of CD burners and the ease by which different people can easily connect with each other over the Internet means that groups are forming around swapping CD mixes according to this New York Times story (registration required):
There are perhaps thousands of other mix makers who burn CD's for a circle of friends or online acquaintances. They are part of a thriving culture of mix swaps, or "burning circles," as Mr. von Lohmann and his friends call them. Some of these can be quite big. One swap involving members of a group Weblog called MetaFilter attracted about 260 participants, each of whom was required to send a mix to five others.