Instead of trying to combat the illegal use of peer-to-peer (P2P) services for file-trading, companies are using those services to deliver ads, reports BusinessWeek.

Agencies such as Skyrider and MediaDefender have seeded a number of P2P networks with licensed video and music files that are either sponsored by an advertiser or contain ads within the actual files. In some cases, such as a video from the band Barenaked Ladies, a portion of the ad is clickable and takes the visitor to a site to download ringtones or other band information.

Since the MGM vs. Grokster lawsuit a couple of years ago, the record industry has, in fact, become more open about ads in P2P networks. Still, hurdles exist in the form of lack of measurement tools and a still-litigious Recording Industry Association of America, which continues to take action against file-traders.

Right now, illegal activity makes up 90 percent of the music downloading market.