If we're going to go this route, I would suggest a check inside the box. Something similar to this Font Awesome icon
It's a neutral symbol
It reminds us of voting (inherently political)
It's easy to do
I think custom badges could be a way to further distinguish the site from others in the network, as well as another step down the pathway to moving out of Beta. I suggest that the icon used could be a rosette similar to campaign rosettes worn in some countries.