Anyone suggest a team project management tool?

My team is looking for a collaborative project management tool. We've used MS Project and Trello, but are looking for something that has the power of Project, the flexibility of Trello but with the ability to do instant updates that the team can see/be notified about. We'd also like rollups of sub-projects into larger projects in a dynamic manner; I know that's something we could get if we had MS Project Server.

We have our eye on Feng Office (http://www.fengoffice.com/web/). Any other suggestions?