HanDBase is a simple
database that has been around a long time for Palm users. Because it is
simple to construct new databases, there are hundreds of simple databases,
with a great number that are useful to the medical field. HanDBase is now
available for the PocketPC and all
those databases that you couldn't use before are now yours for the asking.
See here for more information on this.
Here are some home-grown databases from project members - these can
be used on PocketPCs or Visors.