I'm kind of a nut about keeping personal data safe online. I use 1Password to generate and store all of my login credentials and I get irritated when websites don't let me use 40 character passwords.
Just as important, though, is keeping files safe and secure. For that, I have [Knox], a wonderful piece of software that has an incredibly important job that happens to now be maintained by the amazing developers at Agile Web Solutions
A little background info - Mac OS X, right out of the box, has the ability to create and secure disk images. Just like a virtual hard drive, disk images can store files and folders and can even be encrypted. When unmounted, they just appear as a single, compact file. Unfortunately, creating, managing and maintaining encrypted disk images in OS X can be somewhat of a chore.
This is where Knox comes in. It lives in your menubar when in use (and honestly, I only keep it open when needed but it hardly uses any resources) and allows you to easily create, open and backup encrypted disk images.
Creating and opening images are as easy as two clicks and backing up images can be handled manually or on a schedule with a pre-set backup location. And for piece of mind, should you ever decide to stop using Knox or need to get to a file locked away in an encrypted image, since Knox uses OS X's built-in disk creation process, any images created can be opened on any Mac, with or without Knox.
Syncing encrypted images between computers is a breeze, too. In Knox's general preference panel, just set the "Create new vaults in:" setting to a folder inside Dropbox (you are using Dropbox, right?). Repeat this procedure on every machine you have with Knox installed and they'll all have access to you secure files.
So that's it. Knox, once again proving that the best kind of a app is on that does exactly one thing extremely well.