Personally, I usually just write my name or sometimes just end it without a signature. However, I admit that when receiving an e-mail with a "christian" closing I do feel a little more pressure to respond with one of my own. (I couldn't have them thinking I'm not as spiritual as them!). .
My work e-mail is set up with my "signature": Name, title (best 1st grade teacher ever! LOL), phone number and e-mail.
So, what's your signature?