Can you create a website on Office 365?
It looks like from Microsoft that at the moment the answer is no. Office 365 comes with SharePoint Online, which is Microsoft's web content management system (CMS). However, there is no public licensing model. I.e. there is no equivalent of FIS (SharePoint For Internet Sites) or anonymous access model.
One thing that's different about Office 365 (compared with buying normal Microsoft licences) is that you can buy licences on behalf of third parties. So I guess if you bought a SharePoint Online licence for everyone in the world...! Think you might have to set them all up with user accounts though.
*Note that you can create extranet sites, but you would need to licence all users and give them all individual accounts.