PlayLouder MSP is an Internet Service Provider in the UK (about to launch) that allows and encourages peer-to-peer filesharing. Especially sharing music files!
The cool thing is, that it is actually legal and supported by major music labels.
Here is how they pulled it off: PlayLouder will monitor all traffic between their subscribers. They analyze it and try to recognize the content of the files. Each time a song from one of their partners/ artists/ labels is shared, the rights owner of that song gets a bit of money.
From the FAQ:
How are royalties calculated and ultimately paid to the music rights holders?
PH: “A set proportion of the revenues of the MSP will be set aside as a pool to be split between the various music rights owners. Of this pool a percentage is paid to the record companies and a percentage to the music publishers (via the collection agency MCPS-PRS). The proportion paid to an individual record company will be calculated on a pro rata basis according to the usage within the MSP network of that record company’s music.”