pdb2gnokii is fairly simple. It walks through the PDB and prints to
stdout lines that can be fed to
You can restrict the categories processed by passing parameters to it.
It tries to be clever in order to show all numbers when one contact has several phone numbers, e.g. one home phone number and two work phone numbers. This works for a SonyEricssonT68i as the T68i's agenda knows different types of phones. I don't know if it would work for any other.
See also Synchronize jpilot (pdb and pc3) and GnomeCard (vCard) address database files that I started looking at before writing pdb2gnokii.
Perl script: pdb2gnokii
You will need the p5-Palm modules.