This program views calibrated bitmap maps on PocketPC (WinCE) platform. Additionaly it supports using GPS device to retrieve user position and show it (with other marks) in map - making it very handy for geocaching.
All versions of the program can be downloaded at sourceforge.net.
There is also a screenshot to give you some idea what is this project all about:
If you want to create your custom maps (I guess you will have to :-)), please visit project's wiki page - you can find there informations on how to do it (and more). You can also visit TrekBuddy website, as PocketGPS-Map supports it's maps...
As the project is open-source (GPL), you can also download/view the source code - using SVN (browse svn tree)
You can download the beta release of the new 2008.1 version via sourceforge