I'm sure you will all be shocked to learn, I did *not* get this idea from Pinterest :). (It's ok, take a moment to pick yourself up off the ground).
It could not be simpler to make a bulletin board though. Find a cheapy frame, This is one I found on clearance for $2, and keep an open mind, you could paint it or add embellishments if it's not what exactly what you'd like. Remove the glass and paper, so you just have the backing and put it back in the frame. Use your handy-dandy hot glue gun to glue the corks on to the frame backing.
|bag of corks, and the frame/backing|
|starting to arrange the corks|
|the finished product!|