Pflow random color correction

Hi there,
Here's the thing: I have Pflow setup so that it generates about 3000 planes with pictures of people on them. They need to fly in space and form a word (not important). The problem is I have only 50 pics, and the repetition is obvious.
I thought that it'd be great if I had an operator that would give some random HSV values to each particle when it gets born, but can't find anything like it...
Anyone got any ideas or scripts in mind?

Thanks a lot!!!