I'm old school, so some good old ones I remember are:
The Pusher: Steppenwolf,
http://www.youtube.com/watch?v=rpoEmlxUPeQ
Needle and the Damage Done: Neil Young,
http://www.youtube.com/watch?v=k0t0EW6z8a0
That Smell: Lynyrd Skynyrd,
http://www.youtube.com/watch?v=sV_toedW2L0
Of course, these are classics that also made it into the popular airwaves. Are there any better? (In my opinion, it's hard to top Neil Young).
Bring me up to date.