I have been using HopStop for a few years to find my way around New York Cities mass transit. Until now I have also been using Google Maps on my Berry to find directions but they are not always the best. My wife, Kira, let me know that HopStop has a mobile website that is great for directions on the go. Hopefully Google Maps will add this kind of information but until then this is a great resource.
HopStop has transit information for Boston, Chicago, Long Island, Metro North, New Jersey, New York City, San Francisco, & Washington. The mobile version gives you some great details and looks good in the BlackBerry Browser. They even use the Bold to show it off on the product page.
Check it out at www.hopstop.com/pda and let me know what you think!