I use two different products - both awesome, both web based for team collaboration.
www.teamgantt.com - this makes beautiful, easy to use gantt charts for managing projects and it has dependencies (which I love) - so you can visually indicate that one item cannot start before another item is finished. You can have conversations about specific aspects of your project, share files, etc. Free trial - I think you'll love it.
Priority Matrix - www.prioritymatrix.com - heard about this one through Jefferson Lilly. This is both a native Mac OSX application, and also has web, iOS and Android versions. You can have it open on multiple devices and it autosyncs between them. I use this for managing ongoing aspects of business. Very powerful and customizable. Great for throwing in ideas, notes, links - not just for making gantt charts (but it will do that also). Easy to pick up, hard to put down. Again - free trial - I think you'll love it.