i don't know of one... i didn't know people still used real player / real media...
i don't think such a player exists for the blackberry... your best bet is to convert the file you want to watch on your bb, to a bb compatible format....
Which is a shame. I have 13 seasons of southpark I wish I could move to my phone. I like RM because it can usually keep a 30 show to a bit over 1mb a minute.
Posted from my CrackBerry at wapforums.crackberry.com