Google has just released "Google Apps for your Domain". Say you own "somedomain.tld", and you have some sort of control over its DNS settings.
Google lets you specify an MX record that points to their SMTP servers, to handle all incoming mail to your domain. It's GMail, of course, and it works very well. Say hi.
Google lets you specify CNAME entries for anyhost.somdomain.tld, that points to one of their web servers, with good ol' "Host:" HTTP header-based virtual web hosting. Check out http://frog.futuredigital.com/. Guess what they let you create pages with? None other than Google Lab's pages.google.com
But there's more I've not yet played with:
- Chat: XMPP federation for your domain.
- Calendar sharing.
Screenshot? Yup, right here.
Want your own? Google appears to have limited sign-ups available right here. Not sure how long that's going to be available :)