A utility to edit Type/Creator information can be very useful when working with files transferred from a PC. I think I eventually found "Type Resolve" (by one James Thomson) back in the day, but I can't seem to find a copy right now. Maybe just ResEdit will do?
I can't believe Snitch
is still being sold for $20 after all these years. Too bad.
Perhaps there should be a link to Hypercard Player?
I often found Compact Pro to be a useful means of compressing files, and I think it might be free now. ZipIt frequently caused compatibility problems (it was too easy to forget to turn off MacBinary encoding, rendering the zipped files useless on a PC), and of course Stuffit Lite was shareware.
I also recall finding something called "Finder Fixer" that would increase the amount of RAM that the Finder could use, but I never determined if it could really do all that much good.