Do you have a budding Picasso on your hands? Or even just a toddler who likes to draw on whatever she can find? A and I went to a pottery shop a few weeks ago to make some gifts. Basically, the shop provides various pieces you can choose from (all varying prices), and then you are set free to choose colors and paint it however you wish. At this particular spot, the price of the piece includes the paint and the firing of the pottery. We chose a couple of tiles to use as either a wall plaque or coaster. After we picked some paint colors, I let A go to town painting however she liked. We then topped that off with her handprint (and wrote her name and the date). She did get disinterested every now and then so she'd go play with some toys the shop had available. It certainly took longer to do than it would have sans a 2 year old (we were there about two hours), but she had a great time. And knowing she basically did it all by herself, the gift meant more too.
You can even do this with babies. Of course, you'd have to do the initial painting, but you could certainly paint up their little feet or hands and press them onto your piece. We had several babies with us when we went and they all made their marks--plus, all the mommies had some time to talk.
Once our masterpieces were complete, we left them at the shop so they could be fired. We returned a week later to pick them up. The little monkey immediately remembered that was her creation (and her hand)!
As one of the many bath-toy options, you can buy foam letters for sticking to the tub. All it takes is getting them wet. But instead of buying pre-made letters, make your own! Not only can you create exactly the letters you want, but it's a lot cheaper to do yourself. For the record, the wet foam will stick to the fridge too, but of course it will fall off once dry. But, hey, that could be an activity to keep them busy while you make dinner, at least! 
