An event at which GPG users get together and authenticate each others identity to build the WebOfTrust. Usually a minor part of LUG meetings, conferences (particularly Debian and KDE conferences, because these groups rely on GPG authentication as part of their organisational infrastructure) or other gatherings of the cryptographical aware. Make sure that you up-load yuor key to the appropiate KeyServers before you get involved in KeySigningPartys, because people will expect to find your keys there.

Big Lumber (http://www.biglumber.com/) and keysignings (http://lists.alt.org/mailman/listinfo/keysignings) are both resources to help organise key signings.

If you really can't make it to a keysigning, the next best thing is to send your key to a RobotCA, which doesn't provide verification of who you are, but verifies that a holder of your SecretKey? collects email addressed to your email address.

See also: PGPSigningPartyHOWTO? (somewhat dated)