What I've found that works rather good is having your own internal IRC server, so you can have as many rooms as you need. Everywhere I've worked has tended to h

What I've found that works rather good is having your own internal IRC server, so you can have as many rooms as you need. Everywhere I've worked has tended to have rooms per group/project with the needed overlap. It's also easy to pop someone a PM to join your channel if you need their thoughts. There's also usually a "watercooler" room for that non-work interaction that helps build team camaraderie. Some places have also had bots that display all new commits in the channels, as well as having other custom functionality. I'm not sure if they still do, but Facebook used to have IRC bots that managed deployments.