Most people just don't realize that email is sent in the open and can be intercepted and ready by dozens of people between you and the person you're writing to, which might make you nervous.
I use gpg to sign much of my mail both at home and at work. Here's the (out-of-date?) info on my keys, for reference. Just check the keyserver at pgp.mit.edu, it'll always be correct. I think.
pub 1024D/1F87615A 2002-03-17 Eric Haynes Weigle (Home) <ehw@losalamos.com>, <weigle@gmail.com>
Key fingerprint = 829A 0EBB 9702 5A76 9ED3 9211 D311 4D46 1F87 615A
pub 1024D/59EA9C4F 2002-05-28 Eric Weigle (Work key) <ehw@lanl.gov>
Key fingerprint = 112E F8CA 12A9 771E DB10 6514 D4B0 D758 59EA 9C4F