Quick link: Google Apps, Free version
I rather like Google Apps. Especially Google Mail and Google Docs can be of great use to small teams and could really be all you need. Unfortunately, though understandably (they are a business, after all), Google have been limiting the free offering a bit. Whereas it used to be free for 50 users, you now get at most 10 before you have to switch to a paid plan, like Google Apps for Business.
As you can see from the image above, the link to the free version is not shown on the main Google Apps page any more. In fact, today, I could not even find a working link to the free version anymore by browsing the Google Apps page. There were a few broken ones, which "helpfully" redirected to the Business paid plain.
Ironically, the best way to find the Free version was simply Googling for "google apps free", which led me to the actual
Google Apps, Free version. Just saving the link here in this way for the next time I need to find it.
Update (2012-12-07): Google have discontinued the free version of Google Apps. It was good while it lasted.