Tidying up is more fun with cooking tongs
Erin's found a way to make cleanup a fun part of play (good for motor coordination, too):
My son has always been much happier to help me tidy us his toys if I give him a pair of cooking tongs to use. This has worked from before he was old enough to be into robots or anything - he just loves using the tongs. Tidying up can take a while as each block or whatever has to be lifted and put away carefully with machine-like precision, but it is more fun for all of us. Especially if I get to use tongs too.
Sometimes if I can't find the tongs or they wouldn't work, I suggest that 'The Giant Claw' help me tidy up and he immediately makes his hand into a shape like a claw and uses it like a crane grab to lift things into their place.
Related: 'Toy library' promotes cleanup AND creativity (one of my favorite hacks)