I noticed a fun looking activity at the local library ... a Lego Racing party! My boys love Legos, and they love racing cars, so it seemed like a good match. I took the two youngest boys (right after Colton's soccer game, thus his athletic attire). There were plenty of Legos to make cars, then the kids could race them down the double ramp.
It was fairly crowded (in the picture above, you may see our neighbors the Llewellyn's too!), but there were enough pieces to keep everyone busy making multiple car creations, and the ramp was large enough that many children could race at the same time. While it worked fine for this large group, I also think it would be fun on a smaller scale, where you could really "race" the cars and compare the creativity of the completed cars. I know the setup is available for birthday parties or activities, you can check out the ReadyRaceParty website for more info.
I got a few photos and videos and made a quick little muvee so you can actually catch the cars in action *Ü*