Password Protecting an app

Hello all. Just wondering..is there a way to password protect an app that I keep in my dock, so that when I click on it to open it, I get prompted for my password, and if I don't happen to know it (read: someone else is on my computer) it will deny access?

I've tried google and permission settings, but the best I could come up with is to keep the app in a password protected dmg file, which seems like a bit much for what I need.