This could go a lot further. I once did something similar with a rubberstamp image taken from the web, replaced some of the on-a-curve text in the GIMP, applied

This could go a lot further. I once did something similar with a rubberstamp image taken from the web, replaced some of the on-a-curve text in the GIMP, applied various filters to make the seal look like it was stamped on unevenly, and composited it over the page. Did the trick. Would be neat to have this take a rubberstamp image and do all that work too.