Most of these utilities run on the commandline on your desktop machine, and do stuff on your PocketPC device. Most work on many platforms, not just the XDA.
you can browse the source with viewcvs here
or download the source+executables here
psetmem.exe writes data ('poke') directly to memory.
?psynctime.exe syncs your PocketPC clock with your desktop, and fix the
'lose-focus' problem.
ppostmsg.exe sends or posts windows messages to wince windows. you can also use this tool
to list all the windows and childwindows of your device. ( something which the official wince windows api can no do )
prapi.exe interacts with your wince device via the provisioning API. currently you use this to change policy settings, and set or delete registry keys.