There are many tools which provide weather updates on your desktop like HTC Home Metro and HTC Home for Windows. WinThunder is another portable app for Windows 7 which provides you with weather updates for the city selected, but apart from that it also acts as a shortcut for commonly used folders and apps. You can quickly create shortcuts for folders or apps from the system tray and then quickly access them with a single click.
Just right click on the app and then select create shortcut to add a new shortcut. You can specify it to be an install app or a folder shortcut.
You can change the theme and also add the city from the application settings.
WinThunder is a simple and yet useful tool for your Windows desktop.