One of the cool services that Google offers is the hosting of various services for your domain. Basically, you can brand Google with your own domain including mail, calendar, chat, docs, sites and "mobile" (I haven't used "mobile", but it includes sync services). The service is called Google Apps
The "standard edition" is pretty much the standard services and limits you to 50 user accounts. And 50 people is quite a few for a personal domain or even a small business. Once you need more features or more accounts, its $50 / year per account. Which, truth be told, is pretty cheap since even just paying for anti-spam/anti-virus filtering is about $30 / year for pretty basic service from Symantec of whomever.
At any rate, I found it a bit confusing at first but mostly because I was setting this up in a sub-domain (dl.thenibble.org) on GoDaddy. But once I got in, it's pretty easy. You get this dashboard which shows you which services are activated and you can just click on whichever ones you want and if DNS changes are required, it will tell you and give you pretty specific instructions. But there's a lot. You have to do one just to activate the domain, add aliases for all your services (unless you want to use google.com/apps/mydomain or whatever), and then for email, there's 5 MX records and for chat there's about 10 SRV records.
But now that it's all setup, it's pretty fancy. You can create email groups, use docs, publish calendars, etc. I tried poking around a bit and really all that Google does for stuff like "sites" when you create an alias under your domain is it just redirects the user to sites.google.com/domain/whatever ... So it won't be a replacement for having a web host. But for email, it will just accept mail at your domain so it's a full email service.
And standard edition is free. Did I mention that? Yeah, it's ad-supported, but otherwise free.