Try this - MetrO

Metro provides subway maps including assistance for planing routes from station A to station B for practically every city in the world (provided there is a subway/train/tram service there ofcourse). and Its FREE. They don't have a full blackberry version yet (there is an announcement on the site saying it is coming soon) but in the meanwhile there is a "lite" version that pulls data from their website ie requires active internet connection to work. I have used it on my various Palm or Symbian devices for years - it is wonderful