That does sound like a fun idea
I'd like to be the rebel and use sqlite for small projects like this.
I will put that idea on the back-burner for now.
I'm currently trying to figure out how to automatically size the signatures width based on the length of text.
Only problem with that is:
I have to use an image as a background, Place text on it, Use imagettftext() to check the text width, Create a new image based on the width of imagettftext(), discard the old image, write the text on the new image, then cache it.
It's not impossible, just takes more processing than I want to use in code right now.
As far as the .gif idea,
I haven't done .gif's so I'd really be interested in looking into it.
My only fear right now is XSS/SQL Injects. I've got a lot of friends that don't like me, and they are eager to see me mess up my code.
So, if I were to do what you're thinking, I'd like to get off the http://tgservers.com/