The limitless shelf space of the digital world is encouraging a new era of music titles. RCA Dance Vault is a new undertaking that repackages dance tracks for digital stores. It has a dedicated page set up at iTunes that touts its "unreleased and out-of-print" versions. Some, like Kelly Clarkson's Because of You and Heather Headley's In My Mind, have the cost and length of a normal album. Most are bite-sized offerings of just a few tracks, like the trio of remixes of Icicle Works' "Whisper to a Scream" and the two versions of G.Q.'s "Disco Nights."

What RCA has done is move its catalog online, a storefront that encourages slower moving titles to remain in print. In the physical world some music wouldn't sell enough to keep from being pulled from circulation. Since labels are wise to maximize the value of their catalogs, finding new ways to sell old music will be paramount. We've already seen this from Rhino, which sells Hi-Five EPs, brief five-song artist introductions the label makes available at digital stores.