Here are a few sites that offer a wide selection of different clip art files for free.

http://www.grsites.com/: This is my favorite site and the one I use to find all my backgrounds and clipart files used for this class.

http://www.teacherfiles.com/clip_art.htm: The files up for grabs here are educationally focused and mostly involve the classroom and the internet.

http://www.coolarchive.com/clipart.php: This page offers a wide variety of different categories of clipart. Although there are many sections to choose from, the amount in each section is limited.

http://ausmall.com.au/freegraf/freegrfa.htm: There is a large selection of clipart, backgrounds, buttons and icons to choose from. I like that the site offers real world images rather than cartoon renditions.

http://school.discovery.com/clipart/: This is another site dedicated to offering clipart that is school related. This would be an excellent site to recommend to students working to improve the look of a presentation.

http://www.awesomeclipartforeducators.com/: In addition to clipart, this website also offers fonts, worksheets, coloring pages, and puzzles! A great variety for any clipart searcher!