WARNING! Due to a bug in REALbasic, (yes, there really is a bug in the compiler!) the program cannot be allowed to attempt to open/read the resource fork for itself, the output file it is creating, or the System suitcase. The program is cardcoded to avoid its output file and System, but has to hope you don't rename IT. Make sure the program's name remains "Resource Finder", or that it is not inside the search area, or it will crash in flames when it "finds itself". (you will get a most bizarre error saying that the program has to terminate because the server it was on has been disconnected)
Some things you might want to look for:
"snd " (note the space on the end) These are "system 7 sound" resources
"WDEF" - custom window defs. use MacProcID window properties to access these
"curs" - cursors
I don't recommend looking for anything that's likely to be very large or common, such as CICNs, without limiting the scope of your search. Resource Finder will only search inside subdirectories of the folder you select, and will not follow aliases, so you can pick a small subfolder and scan that for more common items. Resource Finder does not keep copies of each resource in memory, but it does keep a "checksum", so it can tell when it finds a new and unique resource. Since it has to scan an entire resource to checksum it, and then compare against all others it has previously seen, having a lot of them or having them be very big will of course have a major affect on the speed of the search.