Today, the most easily downloadable digital music sits in one of three formats: MP3, Real Audio and Windows Media Audio (.WMA). All three use compression algorithms to shrink huge files into manageable sizes, while retaining much of the clarity and quality we've come to expect in the CD age. The problem is that these formats are proprietary. Microsoft Corp. owns .WMA, RealNetworks controls Real Audio, and the German Fraunhofer Institute owns (and extracts royalties for) MP3. As a result, some smaller vendors and music makers can't afford to play in the digital audio game, while some listeners are bugged by the thought that their favorite tunes are held hostage by corporate-owned formats.