For a small team, I'd say Pivotal Tracker with Flowdock They integrate with each other very well, and you can even plug in github to PivotalTracker and Flowdoc

For a small team, I'd say Pivotal Tracker with Flowdock They integrate with each other very well, and you can even plug in github to PivotalTracker and Flowdock to make everything seamless. I think they are free for up to 5 people as well.