Jigzone.com (http://www.jigzone.com) has jigsaw puzzles that you can work on their site.  It scrambles the pieces and then times you as you drag them into place.  When a piece matches or is properly lined up with another piece, it clicks and locks into place.  When you finish the puzzle, your time is compared to the best time and the average time for that puzzle.
   There is a puzzle of the day, several puzzles along the top, and a whole archive to choose from.
   A puzzle take around 5 minutes to complete.
   Give it a try.