If you haven’t searched “robert downey jr.” in the iTunes Store, they actually have a lot of RDJ films for rent or buy.
One of them is rare — Too Much Sun (1990), which has only been released on VHS (understandable because it’s crap).
A couple of semi-obscure-but-not-really films featuring a young RDJ, like Tuff Turf (1985) and True Believer (1989).
Then there’s Black And White (1999), where RDJ is barely on screen but hey, he’s gay with Jared Leto! You know what, you can watch all of his scenes from that film HERE.
I highly recommend The Last Party (1993), which was RDJ’s documentary about the 1992 Presidential Elections.
BUT WAIT — you can watch that one for free on Hulu!
Full RDJ films available for free on Hulu:
Last year I made an RDJ Filmography Masterpost when masterposts were all the rage. Unfortunately, most of the links are broken at this point, especially after Megaupload went down. I’ll probably try to make a new one at some point.