If you have never read this: http://www.thepetulantpoetess.com/viewstory.php?sid=1570, do. It is not only a hilariously funny fic, it is a highly intelligent one, and the basic idea is one of those rare things that are so good you find yourself wishing you had thought of it first. This bears the highest possible recommendation.
Whatever you are doing, drop it and read this: http://shadowycat.livejournal.com/173531.html?view=2612187#t2612187. I have rarely read such a perfect short story anywhere. I am known to have a way with a twist ending myself, but I rather think that shadowycat's is as good as or better than anything I ever wrote. Absolutely marvelous.