If you work on google docs and have to invite a lot of people to collaborate on your docs then this might get you done faster !
All you have to do is create a group in you google contacts ! You can do this via your Gmail or follow this method. First visit the Contacts page
Now you need a Gmail account and the contact in your Gmail account for this to work (Duh !)
Next time you want to invite just choose that group and you are done !
You can even create events with you collaborators via Google calender one advantage is that Google Calendar keeps track of those who accepted your invitation.
[Via googlesystem.blogspot.com]