Often when I print a hardcopy of a document I will also save and/or distribute a PDF too and SOME of those documents I print on colored paper. It would be a slick DOPDF feature to be able to select paper color for the virtual printer. It SHOULD work just like the real printer - ie. putting something other than the paper color ONLY were ink would fall. I say this wrt graphics since when selecting a background color in the source document file - areas of the BMP graphic within the graphic frame are left white - but when printed on colored paper remain the paper color. Not all source programs will work with a JPEG in transparent base mode.
Like I said - just a thought - and something ACROBAT doesn't do!!
Of course since you no longer support w2k - if you add this feature it won't be of much use to me - I still think it would be a great feature.