Free PDF Editors

Free PDF editor:
PDFill PDF Editor 5
license: Free to try with watermark on filled PDF, $19.99 to buy
requirements: Windows 98/Me/2000/XP/2003 Server/Vista

Free Image and Photo editor:
PDF Editor 2.6
license: Free to try with watermark on documents; $79.00 to buy
requirements: Windows 95/98/Me/NT/2000/XP/2003 Server/Vista

Free Image and Photo editor:
Foxit PDF Editor 2.0
license: Free to try with watermark on modified pages; $99.00 to buy
requirements: Windows 98/Me/NT/2000/XP/2003 Server