For projects hosted on Github, take a look at https://gitter.im https://gitter.im I'm a maintainer of a reasonably big open source project and it works great f

For projects hosted on Github, take a look at https://gitter.im https://gitter.im I'm a maintainer of a reasonably big open source project and it works great for us, since you can link issues/PRs directly and get a Github activity log right next to the chat. It also preserves the chat history, which was one of the big reasons to switch over from IRC.