A useful feature added in Windows 7 is the jump list you can get with a right click on Windows Explorer icon located in the taskbar.
You can also “pin” some resources in the top pinned list:
Because of a bug, if you previously added to pinned list a resource (for example a network share) not available anymore, you can’t remove that resource.
To completely clear both pinned list and recent one, you can delete all the files located at the following path:
%APPDATA%\Microsoft\Windows\Recent\AutomaticDestinations
The result: