I've got GPG set up and ready in case I ever need encryption.
The catch? No one else I know has GPG. So I'm currently not using it, but I have it if I ever need it.
Personally I think GPG is one of the best (if not the best) option, considering the price.
MacGPG is something for OSX users to look at. Some nice plugins linked to as well, like one for Apple's Mail.app.