A neat tip when setting up a new event or meeting in Google Calendar. To add all members of an email group, type the group email address in to the Add box. All members will be added to the attendees list. You can then edit them as normal.
This is very useful when you need to invite a lot of colleagues, saving you time having to enter each email address separately. A good example would be if you have a sales meeting and could enter firstname.lastname@example.org to invite the sales team.