The one you cite is basically a standard drop down menu with a bit of nifty animation to give the 'rubber band' effect when it drops down; to get this effect try drawing a v. short box and shift the corners around and bulge the edges in / out to give the look of the menu starting to drop down, in your next frame move the box down a bit and move the edges accordingly - essentially a bit of traditional animation!
=)
PetitPal.
p.s. If you are not sure how to do normal drop down menus there are, I am lead to believe, loads of tutorials around.