Password Protect Files

I was curious as to how I would go about locking a file so that an individual would need a password no matter what were they to try and open it. I generally keep myself logged in and there are occasionally others that use the computer, I don't want to have to change users every time, I just want to keep a couple of things safe. Thanks.

Check either version tracker or mac update for an encryption program.

I really like Cypher

awesome, thank you guys very much