Mac OS X only: Disk image encryption software SecureFiles creates AES-128 encrypted volumes for securing sensitive files without a lot of hassle.
Installing the application is as simple as any OS X application—just drag it to your Applications folder. Once installed, open the main window to create a new disk image and choose whether to allow Spotlight to index the files (they will only show up if the image is mounted). As noted in the Switching to Mac tutorial, you probably will want to uncheck the box for remembering the password since that would make encryption pointless. Using the encrypted disk images is as simple as double-clicking on the image file to mount it.
Security-focused and more tech-savvy individuals will probably want to stick with the previously mentioned cross-platform, open-source TrueCrypt to encrypt their data, but SecureFiles is a great solution for the everyman. SecureFiles is a free download for Mac users only.
SecureFiles [via Switching to Mac]
