In the old days, my favorite program was S-tools. I think it's no longer being supported, but you can find it here:

[url]http://www.spychecker.com/program/stools.html[/url]

It did a very good job, and it was based on a reputable encryption library, Cryptlib by Peter Gutmann.

If you're looking for something newer and commercial, check out Steganos Security Suite at [url]www.steganos.com.[/url]

MrByte