I am tutoring several talented students, middle school level and early high school level, in mathematics. I am always looking for new sources from which to draw questions. Can anyone recommend books, web-sites, etc. with a interesting questions?
I know of the ArtofProblemSolving.com. I am currently using the books "Challenging Problems in Algebra" and "Challenging Problems in Geometry" by Posamentier and Salkind.
If you haven't been using "The Art and Craft of Problem Solving" by Zeitz, you should. Like, right at this moment. :)
For neat problems... you might want to look into "Which Way Did The Bicycle Go?" by Konhauser, Wagon and Velleman.