Spork for Mac

From Triquetra Software:

Spork is a program that can edit the guts of a files and programs, the data fork. It makes editing the data fork of a file a breeze by including numerous search features, so you can pinpoint a piece of data and go back to it later. You can set default file formats so creating files on the spot is a piece of cake. Changing a file's type or creator is unbelievably speedy. By using Spork, you can get into parts of files you never thought you could! Experiement with the inner workings of your programs and learn what makes them tick, all with Spork. Spork is expected to include resource editing soon as well, with much easier templates than Resedit's to make quick changes a snap. We offer the full program with no restrictions or annoying reminders, however, we expect you to send $5.00 via PayPal or by snail mail as payment.