O Brother is definitely a favorite.
SBF1 mentioned
Immortal Beloved - one of my all time favorite films, irrespective of the music.
The Commitments was also an excellent movie mentioned in the 10yr old OP
Ray was pretty good I thought. Jamie Fox did a pretty good job IMO.
Dreamgirls with Jennifer Hudson was amazing.
Walk the Line
La Bamba
Amadeus (OP also)
Have to say I enjoyed
The Runaways with Kristen Stewart and Dakota Fanning.
Sweeny Todd I liked, but wouldn't call it an all time favorite. I do own it though.
p.s: Personally, I find it amusing posting in 10 year old thread
Good stuff stands the test of time