Add vector or raster digital signature
Submitted by Kip
Some forms require a hand signature on them. Adobe Reader has a feature to stamp such a signature. Note that this is not the same as a digital embedded signature (e.g. PKI).
Without this, the user must print, sign, and scan or manually export the page to be signed, import into something like GIMP, sign the de-vectorized / rasterized version, re-import back into the document via pdftk or some such, and then save.