The "Hidden Game Stuff" section is updated with a few more hidden gems, some added from the old site while others are new.
Little Ninja Brothers (Sound Test, Ending Screen)
Menace Beach (Cheat Option)
Jetsons (Level Select)
Journey To Silius (Stage Select)
Firehawk (Easter Eggs, Stage Warp)
A direct link to the hidden stuff section can be found here.