Online app for project management with a group?

Hi all, I’m new here, but have been reading 43f for a long while and know that y’all will have some good ideas…

I’m starting a new job where it’ll be necessary to track large projects that have lots of players, lots of tasks, milestones, comments, etc. The usual mishigas.

What I’d love to use is some sort of web-enable app that allows everyone internal to see the projects at a high-level, then dig down to see (and depending on their role, edit) administrative detail and related comments/conversations. With a good tagging/search capability. So, very bloggy or wiki-like, but well-organized.

A good wiki might do the job, but I haven’t seen one yet that looks easy and fun enough to use.

I know this sounds hopelessly vague, and probably naive, but I’d love any advice/suggestions – thank you!