Beans.

Yes, beans.  Big ol' lima beans.  What do I have to say about lima beans?  Simply this: they are one of the best toys for kids I've found thus far.  I bought a bag of beans at the grocery store the day after Christmas so the boys would have something to dig with the new giant excavator that Santa brought them for Christmas.  They are very into construction equipment and they do love being industrious.  Fast forward more than 3 months and guess what: my kids still pull out that bin of beans every single day. 
The great thing about these beans is that they are big enough to clean up easily, sturdy enough to not make a big mess, and also big enough that the kids aren't tempted to stick them into any bodily holes (although my kids aren't prone to that kind of exploration anyway).
So, this is my sanity-tip for all of you (like us) who are watching LDS General Conference this weekend.  You still have time before the next session starts.  Go buy a $3.29 bag of lima beans.  If your kids are anything like mine, they will be completely engrossed for at least the next two hours.  This morning our beans have been pushed around in construction equipment, collected into cargo cars on the duplo train, poured into containers in the play kitchen, fed to pretend-pet hedgehogs and the list goes on and on. 

(This was taken the day the beans arrived, back in December.)