Jim,
I use this
Memory-Map Navigator
It runs on my IPaq under Windows Mobile 5.
Included in the package there is a mobile version and a desktop version.
If your phone will connect with Active Sync you can move all the charts, waypoints, routes, and such between the desktop maching and the smart phone.
They now have tracking, AIS, and weather add on moduels.
This previously was from Map Tech until they were absorbed.
And no I don't have any finanical interest in them. Just a satisfied customer.