PELock - is an application that allows you to protect Windows executable files (so called exe-protector). Besides that, PELock allows easy creation of application of evaluation-demo type, which use license key system.

.netshrink is an executable compressor for managed files. It uses LZMA compression library and can decrease your file size by 50%. It can also protect your files with a password. .netshrink uses LZMA compression library to achieve maximum compression ratios. Password protection uses verification based on SHA256 hash function and 256 bit AES / Rijndael encryption.

Obfuscator is a tool to modify x86 assembler source code in this way to make an analysis of compiled code very difficult. It is an unusual tool and the target audience is quite small, but if you're writing assembler code and you want to protect your work from decompilation or just to make it as hard as it's possible to analyze, you might want to try it.