WiseStamp lets you add a personalized signature on any webmail service such as Gmail, Yahoo, AOL mail, and Hotmail.

Some Features:

• Customize your Email signature
  Design style, Font, Size, Color, images etc…
• Add Email Apps with updating dynamic content 
  Automatically Share your latest blog posts, Tweet , Facebook status or Ebay item, etc.
• Easily include your social services& Profiles
  Facebook, Twitter, del.icio.us, IM Services, LinkedIn, and many more..
• Use multiple signatures 
Create business & personal signatures to insert in your emails.
• Add your personal feeds (rss)
• Add your logo or image to your signature

Make sure to check out WiseStamp Email Apps gallery

Find out more on WiseStamp.com