Super Monkey Ball

Successfully complete a level without using a continue to unlock three bonus levels for that difficulty setting. Note: The Master difficulty setting does not have any bonus levels.

Instead of going forwards towards the goal, turn around and go up the little point. Fall off and land on a platform beneath. There should be another goal there that warps you to level 5.

You can combine the power ups to create combos:

Big Glove + Big Glove = Double Glove
Big Glove + Long = Big, Long Glove
Big Glove + Vortex = Big, Vortex Glove
Big Glove + Big Glove + Long = Super Big, Long Glove
Big Glove + Big Glove + Vortex = Super Big, Vortex Glove

Successfully complete the game under the all three initial difficulty settings.

Get 2,500 points during the main game then buy one of the following mini-games for that amount: Monkey Fight, Monkey Race, Monkey Target.

Reach the end of level two. Instead of finishing it, however, search around the area for a little platform that leads down. Fall down there and enter the "other" finish, which leads to level 5.

Collect 2500 points in the main game, then choose a Mini Game. It will be unlocked. Collect a further 2500 to unlock another, and so on.