37signals, an internet SaaS company, provides very intuitive, aesthetic, easy to use and free online tools for personal and collaborative project management. The services are chargeable for higher online storage requirements. The site has video demos to show how these tools work; worth giving a look. List is as follows:
The best feature is that all the conversations, file sharing, to-do lists, etc are archived in a calendar format and can be seen as an overview or can be searched or browsed through later.