Clipart and other "accessory" images are freely available in the thousands, if not millions, online. Many of the same clipart files you would find in Office suites have license agreements which grant them to be used outside of the Office suite they were designed for, and many applications, especially open source applications, have their icons, wallpapers, and more freely available online. You are likely to find many icons and pictures that match what you are looking for perfectly if you know wher to look. Be sure to look at these sites for a good start.