Here are the different plans available:
I registered with their free plan and they gave me a web workspace:
After I logged in, I can create my first project. They also allows me to "create login for other people". This is interesting. I do not know if the users who I created are private users to use my workspace or they are actually regular users.
This is actually very typically B2B web site. You registered for your company and add people from your company to your registration. I remember that when I worked on Oracle Exchange. We have exactly the same company registeration process.
I think that I am actually adding a person to my company profile and inviting them to join BaseCamp.
Here are some comments about BaseCamp found on the web: