WiseStamp is a browser plug-in for Firefox and Chrome (available also for the email client Thunderbird), that allows you to embed a surprisingly wide variety of customized and personalized signatures on your email messages. These include adding links to latest blog post, bookmarks, pictures, videos, Twitter and Facebook status and so on.

Using a WYSIWYG editor you can create and design your signature as you please. Add pictures, links, adjust fonts and color and position the elements to your liking. Then with a click of a button you can insert your signature on any email service you may be using – Gmail, Windows Live, Hotmail, Yahoo etc. You can have multiple email signatures for multiple contacts and purposes.

Perhaps the best feature is the dynamic content that you can embed on your email signatures. You can automatically include the title of your latest blog post in your email signature by simply setting up your blogs feed URL in WiseStamp. You can also share your latest updates on Twitter and Facebook, songs you are listening on Last.fm, your submissions on Digg, Reddit, Mixx and such other social news sites, Delicious bookmarks, and even weather reports.
Rotating signatures example:

Link: WiseStamp Email Signatures that work for you!

WiseStamp Ideas: 25+ best Feed RSS ideas to empower your Email Signature | @ WiseStamp