Cross-platform encryption

I want to save digital copies of important documents on a USB stick, but want to secure them against unauthorized access if the drive gets into the wrong hands, because it would be an identity thief's wet dream. The stick will be part of my household emergency kit.

Today I discovered jFileCrypt, a cross-platform encryption/decryption tool written in Java, and which can run on any platform with Java 5. Aside from the fact that it's free (GPL) software, being platform-independent is what I really find attactive. JFileCrypt supports Blowfish so the resulting encrypted file should be secure.

Alternatives include Mac OS X's built-in ability to create encrypted disk images and GPG. Unfortunately, an ecrypted Mac disk image isn't cross platform, and GPG can be confusing, although I've been playing around with it and I'm getting a better understanding of it. For Windows and Linux users, TrueCrypt looks like a good alternative.

Ideally, I'd like to have an ~500 MB encrypted file or folder on a 1 GB USB drive. On the unencrypted portion I'll keep a copy of the encryption utility so that if necessary, I can decrypt the information even if I don't have access to one of my computers. The password I'll be using is long, non-obvious, and has zero significance to anyone other than me.

If any of my readers have suggestions for cross-platform encryption software that would be suitable for this application, please post them as a comment.