A lot of people want an HTML signature in Gmail, and I've been doing this for some time now and I thought it might be helpful to others...

All you have to do is enable the Canned Responses feature in Gmail Labs... Then you simply create a canned response named "Signature" and just insert that canned response whenever you want to add your signature to an email.

The Canned Response Signature can have HTML, links, colors, pictures, etc...

I want to create a html that will add call me button to the bottom of my gmail email. Basically, I want to add google voice call widget to the bottom of my mails so anyone can call me by pressing the widget when they receive my mail. Is it possible. Appreciate any help on this. Thanks.

mbegin : you can also use a bookmarklet ;-)
http://projets.geekfg.net/?/2-comment+ajouter+une+signature+html+sous+gmail.htm
(in French, but it works well)

I suggested this when I posted about it in October but couldn't get images to work back then:

<< One extra thing I thought of using this for was custom signatures. You could create several signatures – e.g. personal, business, without your phone number, etc. – and then use the canned response feature to drop your preferred signature into your mail. (I thought you could possibly even use this to include images in your signature, but although HTML formatting is allowed, I couldn’t get it to save images copied from the web in the canned responses even though Gmail’s draft messages allow this.) >>

http://blogoscoped.com/archive/2008-10-22-n52.html

Thanks Tony, I guess I missed (or forgot) that. In the group: "Suggest a Labs feature" http://groups.google.com/group/gmail-labs-suggest-a-labs-feature/topics I see so many people ask about HTML signatures, multiple signatures, etc...

It looks like the Canned Response will save Gmail Emoticons, but not embedded images...