Growing up, my most favorite toy to play with was our huge family LEGO collection.
My kids are still a bit young for "real" LEGOS, but the DUPLOS are a close second and get almost constant play time in our house.
Mostly by me.
This is my most recent "Drop-Down Tower" (so named by Jack). I have been making Drop Down Towers for him since he was 9 months old. The towers come in many shapes and sizes, but the main component is a hollow center with a hole at the top, and opening at the bottom, so small toys can be dropped down from the top and out they pop from the bottom... endless entertainment for the kids which buys me time to sort laundry, clean the kitchen, and even sometimes, on a rare occasion, stitch in the middle of the day!