"If you have been living under a rock for the past six months and haven't heard about my customizable WhatPulse sig images you should check them out.
Completely free, they let you choose the colors, font, background, logo, etc. and even upload your own files. Plus, they now track usage so you can see who is viewing your signature image. They work on all forums, even if they are blocking "scripted images"."
As said on the forums. This service supplies excellent forum images, and has been intergrated with the whatpulse.org website a little.
You can automaticly register an account on whatpulse.bounceme.net through whatpulse.org, if you are logged in, you should see a new link called "Forum image". On that new page there are a few instructions, which are pretty explanatory.
The regular WebAPI images on whatpulse.org will be disappearing in exactly 2 weeks, so make sure you switch over before then, if you're using a forum image. ;-) (Don't worry, the oldschool style is available on whatpulse.bounceme.net aswell!)