Mathcats has some ideas for 18 centers spread around a gym that may give you some ideas.

http://www.mathcats.com/grownupcats/...html#mathnight
Some of the Mathcat stations are

Estimation ( jars of coins, sweets..... )

Tangrams (provide pictures of shapes to cover with pieces) and geoboards

Measuring

Bean bag toss and bowling center

Probability

Modules can also be found here:

http://orion.math.iastate.edu/mathni...ities/modules/
Each center has a trifold explaining the activity along with the materials to do the activity. If you provide a set number of seats at a table it will restrict the number of people at a center at any one time.

Some fun ideas I read about :

Wrapping paper symmetry- make your own paper

Topology tricks
Modular bead bracelets- make and take.

Other ideas from

http://www.sci.tamucc.edu/~eyoung/FM...ath_night.html
http://www.thinkingfountain.org/n/noodle/noodle.html
Noodles Design the tallest tower that will stand up using spaghetti and marshmallows. Provide a meter tape on a wall for measuring height.

Spinning tops using cardboard triangles, rectangles and squares with geometric patterns created on them ( and skewers)

3D constructions with pipecleaners and straws- set a challenge eg. make a bridge that will support a book

String Geometry (curve 'stitching') boards with nails spaced at intervals in an L shape and yarn for winding:

http://math.youngzones.org/Curve_stitching.html
http://www.mathcats.com/crafts/stringart.html

Are you square? Know your own body shape:

http://www.sci.tamucc.edu/~eyoung/FMN/square.html