Keychain Secure Notes
Store Secure notes in Apple Keychain
If your looking for a safe place a store sensitive piece of information - your best bet may be Apple's Keychain Secure Notes. The data will be accessible via computer or any iOS device.
This is a good option since third party applications don't have access to this. In addition, it's a bit complex to view a secure note, so you know people won't accidentally find/delete the note if they are playing around with your computer.
Note: Name and Content will not appear in Spotlight Searches. It's a good hiding spot.
Adding a New Secure Note
The only way to add a new secure note is via the Keychain Access application. Using LaunchBar simply type KeyChain and return.
Open up the application. In the Window, select a Keychain to store your note. I recommend using iCloud. Then Shift Command N to create a new note.
I wasn't able to find any limit to how big the note can be, so this might be a good place to store the top secret book that your working on.
You can't store image files in the Keychain.
Viewing a Secure Note
To view any note, simply double click on the note and then type in your computer password.
Need More Power?
If you want more than just basic notes, you might want to check out 1Password. (I haven't used them, so I can't attest to how easy it is to use.) One nice thing is that they have 1 GB of encrypted storage for all your documents.
This is a good way to secure and backup all your work documents!