The Etsumi Display Mirror is a mirror mounted in a simple mechanism that will allow you to frame and shoot your photographs at extreme angles. It works with any 2 or 2.5-inch screen compact camera: just attach the device on the back using two sticky strips and there you go, perfectly framed candid up-the-skirt photos in the subway weird angles at any time.
Personally, I prefer my instant shots to be much more spontaneous. OK, that sounds just wrong: what I mean is not-framed, blurry and who-the-heck-is-that-chin-right-on-that-corner style photos. However, I can see why many people will want this ability. If you can live with opening the mirror each time and its reverse image, prepare to spend $22 plus import duties from Japan.
Catalog page (in japanese) [Etsumi via Impress Photo Watch]