XIcon

XIcon is a conversion program for translating icons between various formats.

XIcon reads:
 * Mac icon resources (raw resource forks)
 * Windows icon files
 * X11 XBM files
 * OS/2 v1.2 Icon files
 * OS/2 v2.0 Icon files

XIcon writes:
 * OS/2 v1.2 Icon files
 * OS/2 v2.0 Icon files
 * Windows Icon files (well, sortof - it's mostly untested)
 * X11 XPM files

Links

 * Source Code at Github