Can I build an addin for Gmail?

Question

Is there a way I can create an addin for my Gmail account? Is GreaseMonkey the only real way?

I use Gmail for customer service, and I'd like to create a tool that looks up the customer and preps a response to them based upon who it is in my database... instead of looking by hand for the client and typing it out.

Answer 1

I don't see how else you could do it. You won't be able to run your own app on Google's backend, so that leaves the client (with javascript and something like GreaseMonkey) and your server (perhaps communicating with the client via AJAX).

Answer 2

You can add gadgets (same as iGoogle and wave) and add them to the side bar in GMail, but you will not have access to the e-mails themselves. You could create small lookup forms and such, though.