By an album intro, I mean the first track that is usually less than two minutes long and serves a somewhat of a mini-song that introduces the subject matter of the album and gives a feel for its general tone and lyrical/musical structure and composition.
A great example of this is "There's a War Going on for Your Mind" by the Flobots off of "Fight With Tools"
Some of these could have serious chating potential if re-written and composed into a full song.
A specific choice would be "Song of the Century" by Green Day off of "21st Century Breakdown"