I'm biased because I cofounded reddit, but one of the best communities for startup founders on the internet is at r/startups (r/entrepreneur is great, too!). Granted there are half a million communities on the reddit platform now, but r/startups and r/entrepreneur every founder (or aspiring founder) should subscribe too. That and r/aww. Gotta have those endorphins.
Business Dad with Alexis Ohanian