Mac/iOS: Sometimes you might want to keep important data with you on your iPhone, but you don't want to just leave it open for everyone to see. Password Pad is a writing app for Mac and iPhone (and Java) that allows you to encrypt your cloud-synced text with either XOR encryption or Triple DES encryption.
Password Pad is all about security. When you create text, you assign it a password, and Password Pad encrypts your text. From there, you can share between devices through email, iCloud, Dropbox or iTunes Sharing. As an actual writing app it's not that different from something like TextEdit, making it a useful distraction-free writing environment. If you want to keep sensitive data on your phone that you can work on with your Mac as well, it's a handy option.
Password Pad comes in two flavours for the Mac. The full version, which supports the very secure Triple DES encryption is $5.49. The Lite version is free, but can only handle XOR encryption. The iPhone version is $1.99 and supports both.