Super Secret Settings
In the new snapshot of minecraft (13w36b) there is a super secret setting in the options menu. when hitting the button an enderman-ish sounds play. Does it do anything or is it just a sound?
Solution 1:
In 13w36b all it does is play mysterious sounds, however a new menu is expected in future snapshots.
In 13w38a clicking the button cycles between a number of shaders:
There are many more besides these three.