Suggestion: A button/way to share a submission you particularly like among your subscribers.
Too many great quality submissions go unnoticed, so I think it would be good to share a particular submission you like with your subscribers. On twitter, you can tweet submissions, and all your followers will see it, and on Facebook, you can like it, so all your friends see it, but there is no way to do it within PMC. I think this could help some high-quality submitters get off the ground and become a known name.
