The battle over music copyrights continued to rage this year. To combat the song pirates, the record industry unveiled copy-proof CDs and AudioGalaxy, one of the biggest music file-sharing networks in the post-Napster era, was shut down. It was a heavy blow, but MP3 hounds just regrouped and shared elsewhere. Meanwhile, U.S. legislators sent a chill through the thriving Internet radio scene by introducing a bill that would require Web-casters, both large and small, to pay hefty royalties.

One of most interesting developments came out of the burgeoning scene of "mash-ups," also known as bootlegs. Taking a tip from culture-jamming guerrillas such as Negativland, bootleggers spliced together a cappella vocals from one song with the instrumental tracks of another -- and the bastard offspring has thrived.

The trick is to meld disparate styles while making the mesh as seamless as possible. While many mash-ups amount to in-jokes for music geeks, several are revelations. Can you imagine Beyonce strutting with Jimi Hendrix ("Work It Out With a Foxy Lady"), or Cher crooning over Echo and the Bunnymen ("I Believe in Killing Time"), or Destiny's Child backed by Radiohead ("Independent Creep")? Maybe not, but some gifted mixmasters have, and when it works, it rocks and slams.