The best I have found is from
http://www.ghisler.com
He has also a program for the PC which is also the best and is now Total Commander, which used to be Windows Commander.
The one for the PocketPC is listed on top of the main page and is free.
I've been using Total Commander for over 10 years and have found nothing better. It does FTP, you can view your AXIM and transfer files back and forth from your PC, find files, delete files, move files, etc.
Read the documentation on both programs and I think you will be amazed by what this program does.
Kent