Two options:
1 (cheap but annoying): Get a USB floppy drive and transfer all the files via floppy from the Classic to the iBook. This is a pain, though, since if you have a lot of files you may end up spending quite a lot of time swapping floppies.
2 (more expensive): Get an Ethernet-to-LocalTalk converter and use it to network the Classic to the iBook and transfer the files via file sharing. This is more expensive (about $99), but you can just drag all the files, get it started, and then go do something else and let it go until it finishes. Plus, if you ever need to network the two machines together again in the future, you can do so.