I use GNU Privacy Guard (aka "GnuPG" or "gpg"), a free replacement for PGP. This allows me to:
Ideally, I'd like to see all email traffic (and most network traffic in general!) get encrypted. This will give us a much more private and secure Internet. We're not at that point yet, but if enough people use PGP/GPG, this will gradually become a reality. Because of this, I encourage everyone to correspond with me using encrypted email, if you can support it. I will gladly do the same with you.
If you're interested in learning more about using PGP for signing or encrypting things, take a look at these links:
pub 1024D/D77B43FB 2002-06-05 Victor Gedris <vic-at-gedris.org> Key fingerprint = 04A9 75C4 36A3 9925 9606 3F5A 4945 A537 D77B 43FB sub 2048g/CFF14C4D 2002-06-05
Here's an ASCII-armoured copy of my key. You can download it from this site, or get a probably more up-to-date copy of it from one of the key servers. I usually use wwwkeys.uk.pgp.net as my keyserver.
Getting my GPG key signed allows me to verify my identity with other PGP users that I meet. The Web of Trust expands on this in a six degrees of separation sort of way, allowing PGP users to build "trust paths" between each other. This way, you don't have to meet every PGP user in the world in order to have trustworthy communications with them.
I have been involved in at least the following Key Signing Parties and webs of trust. Click the links for more info about each.
You can check the key analysis of the global web of trust here: http://keyserver.kjsl.com/~jharris/ka/. The last time I checked, I was ranked #149 with an MSD of 4.0385. You can see the signatures on my key at this link.
I am also registered on Big Lumber, a site where you can find out more about people with PGP keys in your area, and key signing events too.