Here is a fairly complete list that I gathered by using Super Search for 'protect source code'. Remember that using Super Search is quicker than posting a question and waiting for the replies.

• How can I hide the source for my Perl program?
• Protecting Perl Code
• Obfuscate my perl code
• Obfuscating Perl (on purpose!)
• Source Hiding
• Why is it bad to hide the source?
• Protecting perl source code
• Closing Perl Source

Would you look at that? This question has been asked over and over and over.