Swizzler is a simple, elegant solution for encrypting files and folders on your Mac.
To use the Swizzler application you will have to right click (or Control click) on the file that you want to encrypt in the Finder and choose the Swizzler context menu entry.
Encrypts your files using the secure 256 Bit AES encryption algorithm
Simple. Integrated into the Finder, so there's nothing to get in the way of your workflow.
The free version of Swizzler is fully functioning in every respect other than that it can only encrypt individual files which are smaller than 100k in size.
There is no time-limit on it's use, if this is all the functionality you need, then Swizzler is free.