I've been playing with Open Source encryption lately. Lots of cool stuff out there. In particular I really like both TrueCrypt and AxCrypt. As I'm still testing TrueCrypt I'll leave that to a later post after I have a little more hands on experience. However, AxCrypt is much easier to get a handle on and it's really useful. If you need to send a file to someone confidentially, this is a great tool.
You can take any type of a file and encrypt it with either a passphrase or a key file. Passphrases are basically long passwords so that's easy to understand. However key files are even cooler. Say you've got a copy of an mpg file, a large graphic file or heck even a large binary file. You can use those files as keys (think really long, complex passwords) for the encryption. The guy on the other end needs the same exact file to decrypt the message. This is a really powerful and AxCrypt can meet AES 128 bit file encryption standards. You even get compression during the process. One of my favorite features is that it can compress and encrypt the file inside of an exe package so the receiver doesn't need to have a copy of AxCrypt. Good stuff...check it out.