Heart and Souls
I FINALLY got this on DVD (albeit any special features), and I'm happy to say that I loved this movie all over again.
Robert Downey Jr proves even in 1993 (before he got sobered one too many times!) that he was a truly gifted actor. The way he played each of the ghosts that were in his body was remarkable.

I also LOVED the music in this film. My goodness, Marc Shaiman should've (at LEAST) been nominated an Oscar for this film it's that brilliant.
I urge all the Robert Downey Jr fans on this forum (including the Iron Man and Tropic Thunder fans) to go and check out this underrated classic and see for yourself. But a bit of a warning: while there are some really funny moments in this film, the last 15 minutes are pure drama.