Mach-O Browser is a Mac application for browsing the contents of Mach-O (Mach Object) files, including executables, shared libraries, and intermediate object files. This includes files for both Mac OS X and iPhone OS.
A beta test version is freely available for download.
Mach-O Browser aims to provide similar functionality to the otool and nm command-line tools, but utilising the Aqua interface of Mac OS X.
Mac OS X 10.6 is required.