I know Distiller and a few other pricey PDF tools can subset existing documents (at least, I think they can), but are there any free tools any of you know that can subset? I've looked at a few and they seem to do everything up to subsetting.

This isn't necessarily just for Prince... I have a lot of PDFs laying about, some of them very old... even a few that have full versions of Arial Unicode MS (all 30 glorious MBs of it), and I noticed looking through them that many of them have wholly embedded fonts. That's a lot of eaten diskspace.

I don't know of any free tools that can do this. It seems that the world could benefit from an easy to use open source PDF wrangling tool, if anyone listening has the spare time to make one.