I'm fairly certain this has probably been suggested before, but not being premium I can't search the forums, though I went back a couple of pages to see if there was anything visibly recent and found nothing.
Anyways, just had a small idea, strictly for the various "suggestion" forums, I was thinking maybe you could add some kind of one-shot karma count to the original post of a thread, so that the suggestion itself can be rated up or down without affecting, or being affected by the poster's own karma. Occasionally some people get rated down for who they are, rather than for the suggestion they post. I have seen some suggestions that I thought were rather good be rated down to default at first before going up to excellent.
I mean, sure it could just be that someone genuinely thought it was a bad idea, and if someone's being karma-camped they'll probably still get rated down without being read, but a separate karma rating for each suggestion might be beneficial in getting new worthwhile ideas forwarded to devs to consider.
Anyways, just a thought.