Darkvader

No offense, but I don't think you'll learn anything from such sites, it's outdated, kiddish, some of the videos teaches you illegal stuff and might get you in trouble. If you really are serious about computer security, join either defcon www.defcon.org, or the black/white hat www.blackhat.com, they have tons of resources, papers and videos to learn from. BTW, it's not underground and looked down at anymore, that was the 90s era, it's open for everybody and it might land you the greatest job ever earning tons of money .

I don't think there is a way to compile PHP code but there are plenty of php obfuscation software out there both free open source, and commercial. I would suggest you take a look at Zend Encoder ionCube SourceCop Turck MMCache http://www.raizlabs.com/software/phpobfuscator/ ...etc These would certainly help you with what you are trying to achieve. Bear in mind that there will always be reverse engineering. Another idea you can do is to host the application yourself, kinda shared between customers if you don't have a lot of them, but that would entail lots of maintenance and would probably cost more. Any way, those are my 2 cents, and hope it helps.