What? No one mentioned "This Is Spinal Tap" (1984)?
http://en.wikipedia.org/wiki/This_Is_Spinal_TapWhat a perfect parody of heavy metal/hairbands... indeed, it's part of the reason I find that entire genere so ridiculous.
I also like Mr. Holland's Opus and LOVE the Blues Brothers
Here's another film based roughly on the first few issues of Heavy Metal Magazine:
Heavy Metal (1981). Fans of the original SCTV show will recoginze many of the voices of in the cartoon... and comic book fans will recognize the artwork of Berni Wrightson (co-creator of Swamp Thing) in his legendary "Captain Sternn" sequence.
I love the B-17 story...
http://en.wikipedia.org/wiki/Heavy_Metal_(film)
Another movie that prominently features Metal is
Maximum Overdrive with Emilio Estevez. I believe the entire soundtrack was done by AC/DC.