MP3tunes Goes Online founder Michael Robertson's latest venture, MP3tunes went online yesterday with its rights-management free music downloads for 88 cents per song. The new service offers MP3-format music downloads with no restrictions on copying of music files. The new site aims at services such as Apple's iTunes and Napster, which put a proprietary lock on music files to prevent illegal copying. MP3tunes said that the initial service includes more than 22,000 artists and 300,000 songs, representing 30,000 complete CDs. The service also features an online "music locker" to store purchased songs. Robertson launched the company this month after heading up Linspire, a desktop Linux company.