Twiv (Timed Web Image Viewer) is a gadget for Windows Vista that downloads a (webcam) image from the web and displays it in a window of 320x240. The images cross fade into the next image. Clicking on the orange arrow takes you to options where you can set the image URL to download and the interval.
Note: This gadget uses Adobe Flash. Windows 7 64-bit does not have a flash player available yet for the Gadgets. You can still use this gadget by running the 32 bit version of the sidebar rather than the 64 bit. Click here to learn how.
To use this (and other) Gadget on Windows 8, visit this page: http://8gadgetpack.net/