Technically you can get instrumental versions of any songs that have been on Rock Band / Guitar Hero games as people have re mixed the stems from practice mode. So you can find instrumental versions of Pull Me Under, Panic Attack, Constant Motion, and On the Backs of Angles (which already exists in the ADTOE deluxe edition). I guess there'll now be an instrumental version of Metropolis floating around somewhere.
I believe there's a sorta instrumental version of Home on Making of SFAM CD but it's more like a live rehearsal.
Failing that, there's Jammit.