@katmouse
To expand a bit, since I haven't read this thread in a while, there are a couple of reasons for our hesitation towards banners and graphics in signatures.
First and foremost is bandwidth. Believe it or not, we have a relatively decent number of people still using dial-up (like AOL) connections, meaning every graphic they download adds to the amount of time it takes for the page to display, not to mention the amount of data we end up transmitting in each and every post.
Secondly is the growing number of people who view the forum on the go via iPads, iPhones, and other (lesser) mobile devices. Banners suck on small devices. I'm STILL trying to figure a way around our own Google banner for mobile device display (make it display a different, smaller banner based on the device resolution.
Lastly is more of a "netiquette" issue. As I'm sure most will agree, we've all been on some Days forums (or even forums in general) where the use of graphics, images, and banners in signatures completely overwhelms the message of the thread itself.
Based on those few criteria, while the use of an occasional small image (such as a small Christmas image -- not a full banner) might be overlooked for a short time , we kinda tend to try and limit their use as much as possible.
Wayne