I've been crocheting things with variegated cotton yarn -- it keeps me from eating while I watch TV! :-) I chain about three inches to make a circle big enough for a finger, overcast around it, then chain about 18 inches more before making a shape -- maybe a bell or a fan or a star or a flower. Then I move back up the 18-inch chain, chaining through each stitch to double its thickness, and tie off at the circle good and tight.
Sometimes I tie a jinglebell onto the dangle-shape, but I always use a separate piece of yarn, because the bells tend to wear through the yarn after awhile, and I don't want the toy to unravel. My kitties have great fun when I dangle these, and once they capture 'em fair and square, they always drag them off and hide them... which gives me an excuse to make more. :-)
I also make them for the shelter -- the dangle-shape can be slipped around a wire in the top of a cage and then through the finger-circle. I make these a bit shorter, so they'll hang at the right height inside the cages. It makes me feel so good to go to the shelter and see the little ones having fun with things I made for them!