It seems that as the site keeps growing, we are becoming a more attractive target for spammers. However, I will not tolerate this and will keep doing the usual stuff, deleting account and banning domains until they give up. When you encounter some spam links, please downvote them so they do not appear on the front page. Adding a comment mentioning it's spam helps as well, thanks to all who have been doing that, especially @sbruchmann and @gotofritz. Thanks everyone!