Skop, seriously, sigh.... we let you upload avatars 'FROM YOUR HARDDRIVE' since they are generally small, and are guaranteed to be one image. Signatures on the other hand are often text or a mix of text and images, and the images are large. Arranging a system to allow you to upload your own images to the server for signatures could be easily abused and is quite needless when other methods, as pointed out by members in this thread, exist for you to host the pictures elsewhere and link to them.