This site has TONS of resources for structured play, beginning literacy activities, and hand-eye coordination broken down by age from birth and through school years. Stoplight Beanbag Toss - I Can Teach My Child! I own bean bags already!
Sometimes, a simple sponge craft is all you need to keep the little ones occupied in the bathtub. This Cute Little Duct Tape Boat Craft is so alluring that the kids probably won't even want to wait until bath time to play with it.
A fun project for the kids to recycle wine corks and rubber bands from produce into Cork Sailboats With Sparkly Sails from Mama Papa Bubba. Take them in the tub for bath time or outside to the nearest body of water!