Scratch, WeDo, and Collaborative Machines

 Hello all ! .... It was great meeting many of you at the Scratch@MIT event this past week !

I am looking for design challenge ideas for my students and am wanting to do something a bit different with our WeDo kits this year.   Much like the marble challenge at MIT this past week I am looking for "collaborative machines" exercises .... challenges that would require 2-3 students programming their WeDo's to accomplish a task that would require their machine to collaborate with the others to accomplish a task ?

Does the community have any  ideas regarding employing our WeDo kits (or Arduino kits with Scratch4Arduino) in this way ?

Thanks again to the community !

- Rich