My top song/spot combos:
Madvillian - accordion (Fourtet Remix): Exiting the Orange Line at Chinatown Station outbound and walking up the stairs.
Laura Veirs - Secret Someones: When you are on a Green Line train at State and watching everyone run for trains.
Tiki Obmar - Lillypads A: On the Orange Line outbound when the train goes above ground for the first time after New England Med. Center and MassPike and the Back Bay are on the right.
Postal Service - Brand New Colony: (I want to take you far from the cynics in this town...) When the Commuter Rail Train speeds up for the first time outside of North Station.
I'd make a mix tape, but i don't think it would work as well.