On another online forum I follow, they have a thing where someone contributes a particular challenge fabric and cuts it into 10" squares (or however much you have for the number of participants). Each person gets a square of the challenge fabric and, using their own other fabrics, makes a 12.5" square. All the squares are posted online so we can vote on our favorite, and then there is a drawing for someone to win all the blocks.
I've always been very hesitant to join in on anything, but I did that one and it was fun!