For the ones who did not know, if you have your own domain, you can use Google Apps (Gmail, Calender, Docs, Chat, and some more) for free, in case your users are less than 50.
It takes a bit of effort to configure everything, and I have been trying to get Google Apps up and running for my photography portfolio website : www.andpictures.net
All settings have been done, configurations completed, and all I need to do is to wait for the back-end sync to complete and I should be good to go! Being google, it should also work nicely on my Android, which makes it nice!