Interesting technical challenge this last Friday. One Powerbook G3 (second generation, pre-USB, with Ethernet, and SCSI, circa 1999) running OS 9.x. Mostly system standard programs. Have to migrate the folders on the desktop to a brand-new Retina Mac Pro (15 inch) running Mountain Lion.
No SMB/Windows file services on the G3. Appletalk is gone as of Lion. Nothing stock between the two that I could use to share information "as is" (not even floppy drives... )
Solution: I wired the G3 into the switch, kept the Pro on Wifi, fired up FTP services on the Pro from the command line.
I did some web searches on the Pro - IE5 for Mac had a hard time with modern sites... Found a PPC copy of Transmit FTP client at the Panic historical archives, and used Netscape Navigator (remember Navigator?) to download Transmit as well as an old version of Stuffit from the new mac (even then you could use web browsers to browse FTP directories and download).
Got Transmit up and running on the G3, and uploaded all the old folders to the new MBPro desktop.