We have these great shapes from Discovery Toys we've been playing with lately! They have little suction cups on the back so they stick to windows and bathtubs... and make a fabulous sound when you pull them off. :O) We hadn't gotten them out for a long time but Molly (5) found them this week so we put them to use and made a neighborhood with them on our big front windows!
This is a great project to foster imagination and creativity, along with practicing shapes and colors for Ben (2). I was so happy when I heard that later Molly used shapes to create another neighborhood without me so it must have been a fun project for her! (success!)
Unfortunately, I just checked their website and Discovery Toys doesn't offer these suction cup shapes anymore. But! You can also make a neighborhood using shapes cut out from construction paper, similar to what we did in this older post from this past winter!