SharePoint is available just as google docs is, so the natural comparison is there, plus you can access them both for free (as long as you do not mind google spying on your information), additionally, since this is a 'business' utility paying for services would be an option as well.

I assume Jack left off SP since he has an ongoing hate/hate affair with 'pay for software', not because he didn't recognize that SharePoint covers every item on the list, plus much much more!

(no offense Jack)