Here's a demo of Polystyle's PHP obfuscator which works the same as the C# obfuscator:
With it you can obfuscate C# so that you can make your code hard to read. This allows you to sell your source code without anyone else being able to easily reverse engineer it.
Features include:
Strips comments, newlines where ever possible, jumbles variable and function names
Analyzes external code so that your function calls to existing libraries will still work
