I mentioned buying the Playskool Busy Poppin' Pals as a Christmas gift for the girls because I have a preference for battery-free toys. Now that was 20 dollars well spent. The twins love this and I'm actually considering buying a second one just to avoid the inevitable fights over this toy.
Since the popping pals became a part of our family, the girls have learnt to operate the different buttons/switches to make the animals pop. This is one of the two toys that can actually keep them engrossed for over 10 minutes at a sitting. (The other is the cell phone.) 10 minutes of a 15 month old's attention is a big deal, believe me. I had this toy on our last flight and it was a major contributor to my not being led off the plane in a strait jacket.
The wierd thing is Spice only operates one switch and Sugar has learnt how to operate all the other switches EXCEPT for the one switch that Spice has mastered. I don't know what to make of that, but I do know that this toy is a solid A+ in helping them develop motor skills. In fact the twins are feeling so dexterious right now that they've been operating the switches with their chins and feet - basically any body part that can be manuvered.
Disclaimer: I suspect that Sugar's expertise with this is what led to her expertise with opening all manner of door knobs so if you're trying to delay the inevitable bathroom intrusions and bedroom escapes, you may want to skip this toy. But I don't think you should. The kids are going to start messing with those door knobs sooner or later anyway.