Nowadays Ive been searching for a collaboration tool for groups, online of course. It should make files available, have some sort of wiki to write down things everybody needs to now, a calender - that would be the basics. Most important is, that different kind of user groups must be possible for not all of the information must be shared with all existing users.
I will keep you up to date with what I find.

Should contain task management, chat and online status and contact management too.

Project Pier is very nice, open source, easy to go on. Has Task Management, Milestones, User, Messages, File Management but no Wiki and only rude online status management. Probably one of the best out there. Could use some additional user rights management.