Outside i-mails: yes. Includes contact information (address, extension, fax, switchboard) as well as information legally required in Germany for business letters (company registry # and court of registry; names of coporate officers which for us is just the owner-cum-managing director). No disclaimers.
Internal e-mails: no; not even my name as this is displayed in the header anyway.
Never.
I work as a contractor for the military, so virtually all my e-mail is sent to people internally. As such, if they need any specific information about me, they can look me up in the GAL. I usually don’t put anything but the actual content unless I’m addressing some high ranking officers or I’m sort of invoking my division for some authority to get something done.
Also in the required camp. Or I was when I had a job.
Yes, and it drives me batshit crazy when people don’t include their full name, phone number and address at the bottom of their e-mails.
I mean seriously, you set it up once, and then forget it. And after that anytime anyone needs to respond they have all the information right at their fingertips, right at the moment they are trying to repond. It costs you nothing, and the effort is infinitismal compared to the frustration involved in trying to get your number when I’m on the road.
And ferchrissakes put it on the replies as well. What is this, some mis-led-bunny-hugger save-the electrons campaign?
I also include my home e-mail addy, because in my business you never know when a contract will get canceled, and you don’t always get the chance to hand out personal contact info, especially to customers.
I’m with you. I end up on all kinds of email trails. Sometimes from the beginning, some times added in the middle. My emails occasionally get forwarded on to all kinds of other people. So name, employer, job title, phone number and email address got on every email and every response.
I do unless replying to my closest co-workers (like my boss or my direct reports). Or if I’m sending a personal email from my work account for whatever reason (personal email account access is blocked from the office).
Those of you who put your email address in your business email sig…Do you do business with folks who are not terribly bright? 
I answered “no” since I only put my first name and phone extension. Unless I’m initiating an e-mail with someone I haven’t dealt with before. Then I’ll add my title and department. I don’t use the signature feature in Outlook though.
Count me as another one who has an email signature required by corporate standards. It’s set up for you when you start.
Name
Title
phone & fax
company name
company slogan
Legal disclaimer if it goes to an address outside the company
All in required fonts and colors! 
I thought it was a bit draconian at first. Then I saw some of the glurgey signatures some of my coworkers were using prior to the new requirements. Anything to avoid that!
Can I just add that I hate email sigs that include a company logo added in an image format? They show up as attachments in my inbox. It makes it hard to search for the emails with files attached when every damned one from that company shows the little paper clip icon.
I don’t routinely use a signature because my emails go almost exclusively to people at my school site, and they know who I am. I do format my emails like letters, with a salutation and closing, and I type my first name at the end. For emails that go to people I don’t know or to the public, I’ll put in my last name and pertinent contact information.
Mine’s:
Name
Title
All associated Program & University acronyms
Mailing address
Email address w/hyperlink
Office phone number
HIPAA-required legalese
I’m supposed to use it for all non-intraoffice e-mail.
I read somewhere that the higher up the corporate ladder, the less likely a person is to include a signiture. So I don’t add one.
The only signiture I ever do include is
Sent from my mobile device.
Regardless of what computer I send it from. Keeps people guessing where I am.
I wonder how many of the people who answered “Yes” to this poll actually format their signatures according to Internet standards. (Owing to the recent dominance of standards-flouting clients such as Microsoft Outlook, I’m guessing the number is pretty small.)
For the record, the “proper” way of starting a signature is two hyphens, followed by a space, followed by a newline. (After that you can write whatever you want, though it’s recommended to keep it to four lines or less.) Including this separator lets e-mail clients reliably identify the signature and then omit it when replying. (Again, not this seems to bother anyone any more since Outlook unilaterally decided tha top-posting would be a good idea.)
I am required to have Outlook add it to original messages and replies. The format is:
my name
my title, my team
my division
company name
office phone
mobile phone(optional)
fax
corporate web address
Please consider the environment before printing this e-mail
Strangely enough, my email client has yet to accept that I want my signature on EVERY email, so I’ve got to type it out each time. Depending on who I’m writing to, it’s some variation of:
Name
Company Name
Phone #
Address
Of course I don’t write very many emails, and if I do they’re directly to the customer, so it’s important that they’re able to reach me back.
kmshrader, does your client have a “save drafts” feature? If so, you could save a blank email with your signature on it and then just use that as a template each time you want to send a new email.
Well, some of them don’t read threads before posting. 
4 lines, to stay within established Usenet protocol:
Name
Title
Company Name
Phone Number
People might need my physical mailing address once a month, if that.
You and me both, especially in regards to phone number. There have been multiple times when a phone call would have been much more appropriate than an email. Anyone who doesn’t include a phone number on their sig is someone I would rather not work with.
Name
Title, Organization, full US Mail address, phone, fax, email address
(All below the name is arranged horizontally on two lines to save vertical space lines in the archived files and to save paper when printing them. A mandatory disclaimer follows all employees’ emails about them being public info (a gov’t agency)) They are saved virtually"forever"