What do you mean by similar? Stack overflow is very similar on some points (if you filter on tags to have only one language), it's a place where you ask questions and get technical answers, there are upvotes and downvotes, and people who ask for someone to do their homework and some user happily complying.
But I find perlmonks much more learner friendly, because there's too much of a focus on being wiki-ready on Stack Overflow. Your title has to be perfect (easily googlable), your formatting exact, and the ultimate goal is to reach one answer that is THE correct solution and straight to the point. On perlmonks, you won't get that easily downvoted because there's a typo in your title, or you didn't use the correct tag. Here you'd even get upvoted for an answer that doesn't compile and isn't the best one, just because you've added to the debate, it shows there's more than one way to do it, and it gives others the opportunity to explain why one solution might be prefered (and formatting issues and small mistake will be addressed separately in a private message, or through consideration)
So if you're asking for similar communities because you hope to find more of perlmonks, I tried, and I was disappointed.