Basically, I need to be able to do this:
<img src="http://mysite.com/avatar.php?uid=1&size=s" />
The script would need to be able to provide the ability to display the appropriate size depending on the string in the URL; small, medium or large.
The script should also be able to display Gravatars if they're being used, or a fallback image if no avatar exists.
Jake Bunce probably already got me halfway with this post, but I'm not familiar enough with any of this to work it out myself in a reasonable amount of time.
Willing to throw a few bucks at this via PayPal if anyone is interested. I also won't mind sharing the file so others can benefit, if that makes a difference.