Try Yodiz. If you are using scrum or XP then I think you can't beat it. They got a free plan as well. Choosing Yodiz was not a difficult call, considering UX, story management, Issue tracker, project based searchable group chat, scrum board, integration with zendesk, company and project level reporting and above all customer service made it a no brainer for us. Their servers are on Amazon which also contributed to our decision, like all others we wanted to have a reliable service.
Answered Aug 14, 2013
Edited Aug 15, 2013