When we revised our Rules of Conduct earlier this year, one of the changes was removal of the Signature Image Size limitation. The thinking was, "Everyone would keep their signature a reasonable size right?", apparently not. We've a few community members who have been sporting signature images in the 800x400 range, which is a bit extreme. What we've done is limit the size a signature image will display at. As of now regardless of how large the dimensions of an image you stick in your signature are, they will display as 600x150. Images smaller than this are unaffected.