Product review (5 stars): Love the Deluxe Dishwasher Alert
I had one in my other house.  When I moved I really missed it so I was very happy when I found it on Amazon.
It sticks very well to the dishwasher and I always know when the dishes are dirty and/or clean.  I use to have the magnet one but that kept coming off the dishwasher.  This one is so much better.