The pinnacle of all human achievement, "Open Your Heart" from the Sonic Adventure soundtrack, is now available on iTunes, as are a plethora of other Sonic-related albums from across the breadth of time and space. The soundtracks to Sonic Adventure, Sonic Adventure 2, Sonic CD and others can be yours for the paltry sum of $9.99 each, which is a small price to pay for 20 to 30 tracks per album of gloriously ridiculous nostalgia-metal.
Soundtracks for Sonic the Hedgehog 4: Episode 1 and Episode 2 will be available before too long, according to Sega. Head on through to the other side for a full list of what's available now and how to get it.
Update: As it turns out, these soundtracks have been available since last year or earlier. Sega decided to nest the announcement of forthcoming Episode 1 and Episode 2 soundtracks within a reiteration of the availability of its other musical offerings.