EDIT: im aware of the "avatar/forum" in thread title
Since AJ is a forum with a wide spread types of signatures, I figured that many would be interested in what I have to show you.
Here's an example;
First of you will need Photoshop CS3 or higher. I use CS5.
Step 1. go to File>Import>Video Frames To Layers...
In the open dialog, type in "*.*" (minus the quotes) in the file name part and it will show you all file types instead of just movies file types (there is no option to open gifs, only actual movie file types in the drop down file type list). You can also type in "*.gif" to only show gifs. Now, select your gif wherever it's located and when the new dialog pops up, make sure that "From Beginning To End" is selected and that "Make Frame Animation" is checked.
Step 2. Now go to the Window menu (at the top) and open the Animation window. Make sure that it's set on the "Animation (Frames)" tab
Step 3. Go to the Image menu button at the top and select Image Size... and change the global size there. Make sure the the measuring unit is set to Pixels and change the amount to 85x85 pixels. Or if it's an irregular rectangle shaped image, set the largest size to 85 pixels, and the other dimension will scale down proportionally.
Step 4. Saving and optimizing; If you go to File>Save, you won't be able to save an animated gif. Just a still gif image with little options to optimize. So what you have to do is go to File>Save for Web & Devices... ( Remember to select gif, by default it will choose PNG-24 )