HTC Home is a free, open-source Windows applet that displays a clock and weather forecast on your desktop.
Despite the name, the program has nothing to do with HTC, the company; the author simply wanted to reproduce the time and weather applet on HTC Communicators.
He's done a good job, though, and the display looks fabulous. It's large, packed with information (day, date, current temperature for your location, weather predictions for the next four days), and you even get animations appropriate to the current conditions. So on a grey day, for instance, you might have animated clouds passing in front of the clock display.
Distracting? Maybe, but fortunately you can disable the animations, if you prefer. And the program's settings box allows you to customise just about every other aspect of its operations: the weather location you want to monitor, the applet's position and size, your preferred time format (12 or 24 hour), the applet fonts and more.
Of course all this power comes at a price, and HTC Home uses more RAM and CPU time than the simpler competition. If you need a clock and weather applet that looks great, though, and you can spare the system resources, then this could still be an excellent choice.