It's been done on the show, but I didn't see a list here on the forums...
1. The Blues Brothers - The Blues Brothers
2.Sing Street - Sing Street
3. Stillwater - Almost Famous
4. Spinal Tap - This is Spinal Tap
5. Figran D'an and the Modal Nodes - Star Wars
Honorable Mention:
Marvin Berry & the Starlighters - Back to the Future
The Weird Sisters - Harry Potter and the Goblet of Fire
The Soggy Bottom Boys - O Brother Where Art Thou?
School of Rock - School of Rock
The Ain't Rights - Green Room