Music fans are uploading playlists they’ve created to music services and tagging them thematically. It’s “a phenomenon that some researchers predict will dramatically change the online music business before the decade is out. IMixes are the online cousins of amateur cassette-tape and CD mixes created over the years by countless music collectors as soundtracks for parties and road trips. Many of the playlists focus on a theme — and many of those on a personal one, whether the subject is a lost love, a class reunion, a nasty breakup, duty in Iraq or a new romance.”