This widget rocks!
Colorful, clear graphic description of which train is coming, when, to get you to your destination. The widget updates itself every minute telling you how soon the trains are. Optional spoken announcement. Map-based station selection. Doesn't need an internet connection to work.
The only improvements I'd like to see are, an indication of the "bicycle blackout" (rush hour) trains, and a feature where you can save frequent trips, and quickly select them.