Personally, I have sig images turned off, and I also UnTick the "Load Images" Checkbox in FF.
Pretty much, the only thing I download from websites is the text. I even ban almost all Cookies, even log-in ones!
This is because of my interneting charge here at Uni ( Costs 11c per MB, which is a total rip-off and I'm poor enough as it is! ), but either way, I click the text links in people's sigs purely because they are text links. From my POV, it's nothing fancy, and nothing overly intrusive ( for all I know, it could be a 800x600 image, but, meh ).
Just pointing out that the smart browser clicks links because they're interested in content rather than flashy banners.
In summary: I agree whole-heartedly with David
Jess.