Directions:

GASMASK - Unlimited Health
1WITHFORCE - Campaign Level Select
CHOSEN1 - Unlimited Ammo
FRAGFIESTA - Unlock Multiplayer Levels
CORDE - Unlock Padme
ROGERROGER - Use Battle Droid in Geonosis Academy
WAT TAMBOR - Use Super Battle Droid in Academy
FUZZBALL - Use Wookie in Jedi Academy
CINEMA - All FMVs
YUB YUB - Unlock Bonus Objectives
SAYCHEESE - Development Team Photos

Hear the Ewok song:
At the options screen, press Up, Up, Down, Down, Left, Right, Left, Right, B, A, Start

Unlock list:
Get the indicated amount of bonus points to unlock more items.

5 bonus points - Raxus Duel MP Map
10 bonus points - Thule Moon Control MP Map
15 bonus points - Rhen Var MP Map
20 bonus points - Jedi Academy MP Map
25 bonus points - Unit Viewer
30 bonus points - Making Of FMV
35 bonus points - CD Player
40 bonus points - Sketchbook
45 bonus points - Yoda for Multiplayer