Ask HN: How do I *easily* edit and sign PDFs in *nix?

Hi<p>I read quite a bit of material on the paperless office recently.<p>Here is something that I came across that isn't as easy as I thought it would be.<p>In order to edit and sign a PDF (supplied by a vendor) I'd have to 1) print it 2) scan it 3) send it as a PDF.<p>I need a SIMPLE to use GPL tool that can take a PDF, allow me to edit in overlay mode (typed text) and append my signature.<p>I slogged through an hour of PDFEdit and GIMP editing this morning to get something with 4 fields and a signature done, and frankly, I'd rather buy a printer.<p>Any suggestions on this? I must be missing some application out there. Other suggestions welcome.