I have two classes of personal keys: normal keys, and a key-signing only key. Normal keys are what I use in day-to-day activities, for things like e-mail, signing documents or files, etc. My key-signing only key is used only in operations dealing directly with signing other keys, and is otherwise kept off-line. The general idea is that the key-signing key involves a lot of work getting people to sign it, and so that work should be isolated. The rest of my keys, however, can be created and revoked at will.
Before I sign anyone's key, we must participate in a key signing. During the key signing, you and I will exchange key fingerprints, and I will compare the identity in the key with some sort of identification, which must have a photograph (i.e. a driver's license or passport).
Once you and I have exchanged fingerprints, I will import the keys, verify that the fingerprint matches, and sign the key. I'll then send the key back to you. You can then add that key to your local keychain, send it to a keyserver, etc.
You can find a copy of my key-signing only key here or download it from a public keyserver (I tend to use pgp.mit.edu, which peers with several other public keyservers). My key-signing only key ID is 0x985558d3.
pub 4096R/985558D3 2007-03-26
uid Thomas Leroy Kula (Key-signing only key: http://www-personal.umich.edu/~tkula/pgp/) <tkula@umich.edu>
I will use this key to sign other keys, and to sign blocks of text needed during the process of exchanging keys. Otherwise, it is not used.