i received several comments on the awkward family photos site i linked to a few weeks back. one person (thx dionna) even sent me a link to another, similar site.
i find the key factor to success for funny picture sites is not just the picture itself but the commentary the host attaches to a photograph. without the proper wit, the full potential is not met. here's an image/caption example from the site dionna sent my way:
It's a vagina, madam, not a clown car.
i don't know that you're going to do any better than that. if this were the olympics, that would be a solid 10.0.
check out his other work.