"Pick up the Guitar Hero World Tour Complete Guitar Game before December 31st and choose 5 free downloadable tracks," promises the official site, which says to "check back soon to redeem your 5 free songs" and further specifies that the promotion is only valid for the PS3 and Xbox 360 versions.

The "Complete Guitar Game" bundle packs the multi-instrument music game and a wireless guitar for $85. The offer only mentions the "Complete Guitar Game," indicating that buyers of the $190 "Full Band Kit"--containing the game, wireless guitar, wireless drums, and microphone--or the stand-alone game will not be eligible for the promotion.

Specifics were not offered, but the free songs are likely to be pulled from the library of existing DLC, which are generally priced $2 per song.

Thanks to Shacker hillemania for the tip.