login pop as of dropbox.com or user setting as google

Hi I want to know how to implement the below functionality as below

1) when you click on your user name in google account it will pop down a panel that 
contains  setting details of user.       
                                or

2) if you click signin in dropbox.com or codeproject.com,a panel will pop down asking for user login.


Which controls are being used for this and how they are inplemented. can any one share me code or show how to do it?