Two of the hippest billion-dollar corporations Starbucks (SBUX) and Apple (AAPL) are teaming up once again. The coffee king of Seattle is set to unleash a wireless iTunes music service in select markets, for use in its coffee houses. To mark this event, Starbucks is handing out 1.5 million free Song of the Day cards each day between October 2 and November 7, resulting in 50 million free digital songs from the AAPL downloading service.

But don't stop in thinking you can download just anything. The free song will be a specific track, kicking off with Bob Dylan's Joker Man. In total, 37 artists will be featured, including Paul McCartney and Joni Mitchell, who were the first 2 artists on Starbucks' own Hear Music label. Other artists participating in the promotion include Dave Matthews, John Mayer, and Joss Stone.

Also starting October 2, SBUX will offer iTunes digital-release cards, which enable users to download a full album of music and bonus material online. One of the first featured albums will be KT Tunstall's Drastic Fantastic, available for $14.99. SBUX customers can also scoop up a reloadable purchasing card that includes 2 free iTunes downloads upon registration.

This marks the second recent collaboration for Starbucks and Apple. Earlier this month, the pair announced a plan that will allow iPhone users to directly download songs heard playing at a Starbucks location into their mobile device. People using a laptop with iTunes software will also be able to use this new service, which the company hopes to introduce to all U.S. stores by the end of 2009.

In early trading, SBUX is virtually unchanged; AAPL shares are up 1.8%.