HexSource

 Source Edit is shipped with a hex editor called HexSource.

 Author:   Joacim Andersson
 Homepage: http://www.brixoft.net/prodinfo.asp?id=3
 Family:   HexEditorFamily
 Platform: Windows
 License:  GPL

This editor is based on frhed (the Free Hex Editor) originally created by Raihan Kibria.

Some of the features of HexSource

Native 32 bit Windows application: long filenames supported, editable file size limited only by available system memory.
Small program size, loads fast.
Cut, copy & paste binary values.
Syntax for describing byte, word, longword, float and double binary values in text form to use with find and paste functions.
Directly enter hexadecimal values or text in main window (overwrite or insert).
Compare files.
Find/Replace? any combination of text and binary values.
Bit manipulation.
Export as hexdump to file or clipboard.
Automatically adjust bytes displayed per hexdump line to window width, or set bytes per line manually.
Choose font size, character set (ANSI or OEM), colors of text and background.
Intel or Motorola binary format.
Can be used as "Send to"-Target.
Set bookmarks to easily access offsets in the file.
Load files partially.
Drag and Drop.
Apply binary templates for structured information.
Hard disk sector read access.
Cryptography support.
Launch the current opened file using its associated application.

 Screenshot: