It all depends what kind of SW you are looking for:
1. SW to read the log from your iTrek Z1:
- Use
SourceForge.net: MTK GPS Datalogger Device Control
2. GPS info software - some should be delivered with your iTrek Z1 (or go fetch it on the transystem site - the iblue 747 and 757 are similar devices).
3. Navigation SW.
Currently some free SW and maps are under developments. There are places in Europe where the map is quite good, others where it is not quite filled yet. Your site:
OpenStreetMap or
Main Page - OpenStreetMap . If you look good enough you should be able to find the applications for your PDA.