[krrishd]

It's been a while since I've taken a look at the landscape, but Telescope is a tool that's built explicitly (or at least used to be explicitly) for building Reddit/HN style communities (http://www.telescopeapp.org/).

In addition to their actual software, looks like they have a nice little guide about actually building thriving communities on their tech: http://www.communitybuildingguide.com/

[charleswzx]

Telescope was one of the first things I checked out. They appear largely deprecated though, and have moved on to their new framework, http://docs.vulcanjs.org/