I am envisioning a place with different stations set up, manned by parents and older students, like at a children's hands on museum. All the stations would have some fun math related activities to do.
Here are some ideas I had:
3D spacial table - w/ things like perplexus and tetraxis
Game table w/ games, there's so many of these we'd have to break them up into themes - Set, Quirkle, Rush Hour, ...
Tiling activities - like fractiles, blokus, pentomino,
Puzzle table -
Oragami table with instruction books and some folded inspiration
History table(s) - with Babylonian, Egyptian, Roman and Arabic examples and puzzles
Chess table with sets set up to play, chess puzzles, etc...
Story table with selections from Living Math reading list - this could be one where a host read to kids, kids read to themselves, or parents read with their kids
Family math table with math games from the book
Music table(s) - pitch and rhythm are both very mathematical, but what exactly to put out?
A friend suggested Bucky balls and Zome Tools.
And here are some a friend emailed to me:
Vi Hart's videos are full of interesting ideas.
I got really excited about stars for a while, and wrote a Logo program to space N ticks evenly around a circle, so that I could print them out as templates for star doodling. Her other stuff is neat too.
Calculating pi by measuring various round objects and doing the division is
pretty fun and really helps kids understand the meaning of pi.
Playdough for fractions? Make a ball, cut it into wedges like an orange,
Laminated hundreds charts are fun for coloring patterns on.
Older kids could make paper slide rules and learn how they work.
Roll 2 dice and graph the rolls to see if we could generate a bell curve.
Build paper models of platonic solids (printable templates @ Wolfram)
And here is some inspiration for the web:
Constructing the Universal Classroom
What ideas do you have?