FtpView is awesome, but limited to one file drag&drop at a time, no folder or multi-file transfers. SuperExplorer is the shareware version sold through Applian, with added features like tap&hold and auto-sliding tree views when dragging... FtpView is freeware. Just install from the CAB appropriate for your device, meaning not 'colour PPC' but rather the ARM version. Lots of versions in that ZIP file.
Cambridge makes an FTP server for the PPC, and also a couple of FTP clients. They're at cam.com.
I think ScottyFTP might still be available from RukSun, but that program stank. I was very upset with them after laying out cash for it in 2000 and seeing so very many erors and really laughable support.
There are probably others. I know Dan East's old DXplor offered plugins like Resco does now, for ZIP and for FTP and registry editing. It might still be available somewhere. Never had much luck making the main program work to my liking, so I didn't purchase it which would have enabled the plugins.