HexEdit is a hexadecimal file editor that handles both data and resource forks. It is the most widely used editor of its kind on the platform, and can handle file sizes of up to four gigabytes with ease, yet has memory requirements of less than a megabyte (with color turned off). It can compare whole files for similarities or differences and will soon be able to do so for any subset within the files. A great tool that allows you to edit and analyze the contents for either the data or resource fork of any type of file.
Mac OS X 10.4 or later