I did one on another forum where a dozen people agreed to each pick a block according to a theme (it was stars). Each person made one of each block in her own fabrics and made her own quilt.
It definitely made me reach a little and try blocks I wouldn't have normally chosen. I think I could easily pick 12 star blocks, but it was interesting (and encouraging) to work with others.
Maybe you could do something like that on this forum?