Notepad++ is a free source code editor and Notepad replacement that supports several languages. Written in C++ using a pure Win32 API, Notepad++ provides greater performance and a smaller program size. It's true power, though, comes with its programming language syntax highlighting and the ability to customize the program as required by the particular users.
HxD is a free hex editor that allows you to edit the raw binary content of a file or a disk. This enables you to analyze malware, patch programs, repair harddrive tables, perform file comparisons, manipulate save games, and create game trainers and cheats.
WinMerge is a text file differencing tool for Windows. It can highlight and reconcile entire directory trees of files, showing you exactly what has changed and where between any two versions of the file or directory tree being examined.
Resource Hacker is a free program that allows you to view, modify, rename, delete, and export resources embedded into an executable file. These resources include icons, menus, dialogs, sounds, strings, and other binary objects such as embedded files.