Nope. Go the the User CP, edit your sig, and you can click the yellow "insert image" icon and paste the url for the image you want. You'll need to upload something to paste ther, of course. I use http://www.imageshack.us/ most of the time, but there are others like photobucket, etc. Imageshack can even resize for you, if you need. After you upload it, copy the very bottom url it gives you, and paste it using the button I mentioned.