From Vivid Designs:
EasyCrypt is an easy interface for securely encrypting files. EasyCrypt has lets you create your own encryption-key file, which can then be kept secure or sent out to other people who may need to decrypt files. Once the user has created this key file they can use it to encrypt and decrypt files with just a few clicks of the mouse. Also provided is a secure file-deletion screen, which will allow the user to securely delete a file in the knowledge that it won't ever be retrieved by anyone. EasyCrypt can run on Windows Startup and is then always available from the System Tray.