Google Calendar is another one that I use all the time in a personal capacity. The option of sharing calendars is handy - I have a calendar that's shared with my extended family so I have no excuses for not knowing whose big birthday celebration is coming up and when, and back when I was a Guide leader in Ireland I shared a calendar with other leaders so we all knew what was coming up locally, in Dublin and nationally within CGI. I never thought of it as a tool that can be embedded within a website, but I see how that could be very useful.
A question that arises from all this use of Google products in a work environment: how comfortable are we with sharing organisational information with a global company? If it becomes the norm to use email, documents sharing, calendars and other tools from a particular company, should there be limits on what types of documents are shared there? Maybe it's not an issue in the university sector - what do other people think?