I've posted a few screenshots of my email signature here on my blog over the past few years-back in 2008 I posted an image of my signature with a message designed to discourage email printing and last summer I posted an image of an updated signature with links out to my social media spaces. With the announcement from Google about gmail's capacity to include rich text formatting, I updated my signature with simple linkable social media icons to replace the long URLs (my school uses Google as our email and collaboration platform). I like the way my updated signature looks and I hope it models the professional use of a variety of social media tools (the folder, by the way, is a link to my professional portfolio space).
How about you...what does your email signature look like??