Basecamp

I've just heard about Basecamp today which is an online collaborative tool to manage projects, including communication, to do lists, milestones, etc.

The application is freely available, however to use it for more than one project at a time does cost money, but not a huge amount. According to the website "Basecamp takes a fresh, novel approach to project collaboration. Projects don't fail from a lack of charts, graphs, stats, or reports, they fail from a lack of clear communication. Basecamp solves this problem by providing tools tailored to improve the communication between people working together on a project."

I'm planning on having a play, but would be curious to hear if anyone else has heard or used this?