Keeping kids interested in the seder

Received via a community email list:

We'd like to keep our 4- and 6-year-olds alert and excited for as long as possible during the seder. Acting out parts of the haggada has been suggested but we're drawing a blank on how to do this realistically yet without delaying the proceedings too much.
Has anyone out there in Cyberspace done this successfully in previous years? Can you share your ideas?
Also, any idea how to act out the MAKOT (plagues)?

Despite not doing anything unusual at our seder, our kids manage to stay awake. Our oldest set the precedent at his first seder at age 2.5 weeks. My parents were supposed to join us, but they had been in town for the birth and brit and couldn't bring themselves to make a second trip so soon. We declined an invitation to the seder, which was just as well, because our newborn stayed awake for the entire time; my husband and I took turns walking with him.

As for older children, it helps if they have learned about Pesach in advance, and have a pictorial haggadah. I've heard of props and quizzes, but I think the most important thing is to pay attention to them, explain the text on their level, and have them fully participate in every aspect of the seder including serving. After all, the seder is full of all kinds of interesting activities; we just need to point them out.

Another thing that helps: We serve only two courses and generally end by midnight. And don't forget the naps.

Please post any suggestions in the comments.