ResFool for Mac

From The La Jolla Underground:

Welcome to version 1.0.1 of ResFool, the only Mac OS X native resource editor with full ResEdit template support for under $20! ResFool allows you to create and edit a huge number of resource types under Mac OS X.

Template Based Editing

Use one of the 100 included templates to edit existing resource types. If those aren't enough for you, you can construct your own using 94 template types, or use one made by other people in the active Macintosh developer community. The possibilities for editing binary data in a semantically enriched environment are endless. With support for nested lists, skip fields, arbitrarily aligned data, strings, numerics and more, ResFool templates allow for editing a diverse range of data.

Custom Editors

ResFool also comes with several custom editors. There is an editor Apple Event terminologies ('aete'), Pascal string lists ('str#'), styled text ('TEXT' with an optional 'styl') and versions ('vers').

Modern File Types

Edit and create traditional Mac resource files, or choose to store the resource fork in the data fork of a file (as used by modern Bundles). You can even edit bundles directly, displaying all the individual resources in the bundle, including those stored in individual files or in data-fork based resource files.