BreakPoint Software, Inc. Home of Hex Workshop, the Professional Hex Editor (and sector editor, base converter, and bit manipulator). [Commercial] http://www.bpsoft.com/

Hexedit Shows a file both in ASCII and in hexadecimal. Text mode program for Unix. [Open Source] http://www.chez.com/prigaux/hexedit.html

HexTool A small and fast binary file and hex editor for DOS, with mouse interface. [Shareware] http://www.durward.com/hextool

The HT Editor A professional executable file editing tool which currently supports the MZ, PE and LE file formats including code analyser. For Windows and Unix. [Open Source] http://hte.sourceforge.net/

Hackman An advanced hex editor and disassembler. News, support and related products such as language packs, plugins and add-ins. http://www.technologismiki.com/hackman/

Shed Easy to use hex editor written for Unix/Linux using ncurses, with a friendly pico-style interface. http://shed.sourceforge.net/

BSD ex/vi 3.7 ported to modern Unix systems The original vi source code, with a few necessary modernizations. http://ex-vi.sourceforge.net/