Twitter Your Signature
blog.twitter.com/2008/03/twitter-your-signature.html
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Use Twitsig.com: "Many forums, Blogs, and other web services allow you to have images as part of your signature. twitsig.com allows you to display your current twitter status as an image."