If you ever need to entertain kids: Dump toys out, then start playing with them.
Once kids see how fun and cool those toys are, they'll be there playing too. (And then if you're like me with my kids at home, you'll try and sneak away to get some work done while your kids do their "work.") This trick works especially well for toddler/preschooler set, but I think it would even work on adults.
This afternoon, when I needed to get some work done for Mr. Emily's business, I laid out a bunch of junk on the kitchen table. After sitting down and playing for a minute, I left Kid 1 alone, and had 30 solid minutes of productive time.
She was building towers and houses, and was very engaged. After playing at the table, she moved onto building a cardboard box house from a salvaged recycling bin item.
If I would have just said, "I need to get some work done, find something to do," chances are good that her mind would have been blank, and that finding something to do would have been impossible. Usually, when I set out toys or an activity, engaged playing is the result.
So, what about you? Do you already use the "Dump and Play" method? What's your best tip for entertaining kids?