
Specify a Flickr username or tags which the program will use to download wallpapers to your computer. You can have it rotate the wallpaper at regular intervals, like once a day for example.
It's an executable program which will run in your system tray. You can place a shortcut to it in your Startup folder if you want this to start every time your computer starts.
You can keep track of the wallpapers you've downloaded on a text file so that an image isn't shown more than once. Open this file in a text editor and delete all of the text if you want to clear out the history.