Nevertheless, a variety of Internet radio stations and music services are hoping to give Sirius XM a run for its money. Having successfully gone public, Pandora ( P) may be the most-in-your-face of Sirius XM competitors. It has made tremendous strides in carving out a loyal user base and offers free and paid service tiers. What may work to Sirius XM's advantage in head-to-head competition is that the company, post-IPO, could face shareholder demands for increased revenue that leads to more advertising, a potential deal breaker luring listeners back to the satellite service's ad-free content. Sirius XM also offers a lengthy roster of talk-based programming, something the all-music Pandora has yet to branch out with. Nevertheless, Pandora has the brand-name recognition and business deals that may lose Sirius XM's executives some sleep. Its free music program is the most downloaded of its kind in Apple's iOS and Google's Android app stores. It is also picking a fight in the automaker playground, embarking on deals with Ford Chevrolet, Daimler ( DAI), Cadillac and BMW. On Oct. 6, Pandora announced that Toyota is offering an embedded version of its service on 2012 Camrys and Tacomas via its Entune system. Pandora controls are made available via the dashboard radio, and drivers and passengers can connect using Android, Blackberry and iPhone smartphones. The online music service Rhapsody has been around since 2001, making it one of the oldest of its kind. Bought by RealNetworks in 2003,it was spun back on its own last year and now has about 1.5 subscribers accessing a library of 11 million songs. On Oct. 3, Rhapsody announced it has signed an agreement with Napster, the once notorious file-sharing service long since gone legal and now a unit of Best Buy. Rhapsody will acquire Napster subscribers and other assets, and Best Buy ( BBY) will get a minority stake. The transaction is expected to close by the end of November.