Wouldn't it be great to know exactly how kitty is feeling at any given moment? Although mood stones may not be scientifically proven to indicate your cat's mood changes, they can still be fun to experiment with. Moody Cat collars are adorned with pewter-set moodstones that have small round cutouts behind them so they come into direct contact with kitty. According to the manufacturer, the stones are sensitive to the cat's body temperature and they change colors according to her moods. (You all remember mood rings from the 1970s, right? Same idea.) So if the stone turns blue-green she's feeling relaxed and cuddly, but if it turns black, look out-she's feeling cranky. They come in several patent leather and cowhide faux prints, including giraffe and red crocodile.