When you enter these codes at the 'Codes' menu at the bar in the cantina in Mos Eisley the following effects become enabled in the game.

Unlock Admiral Ackbar:
Enter the code ACK646

Unlock Battle Droid Commander:
Enter the code KPF958

Unlock Boba Fett (Boy):
Enter the code GGF539

Unlock Boss Nass:
Enter the code HHY697

Unlock Captain Tarpals:
Enter the code QRN714

Unlock Count Dooku:
Enter the code DDD748

Unlock Darth Maul:
Enter the code EUK421

Unlock Disguise:
Enter the code BRJ437

Unlock Droid Tri-Fighter:
Enter the code AAB123

Unlock Ewok:
Enter the code EWK785

Unlock General Grievous:
Enter the code PMN576

Unlock Greedo:
Enter the code ZZR636

Unlock Imperial Guard:
Enter the code GUA850

Unlock Imperial Shuttle:
Enter the code HUT845

Unlock Jedi Grapple Move:
Enter the code CLZ738

Unlock Ki Adi Mundi:
Enter the code MUN486

Unlock Luminara:
Enter the code LUM521

Unlock Padme:
Enter the code VBJ322

Unlock Recolored R2D2:
Enter the code EVILR2

Unlock Taun We:
Enter the code PRX482

Unlock Tie Interceptor:
Enter the code INT729

Unlock Tie Fighter:
Enter the code DBH897

Unlock Stormtrooper:
Enter the code NBN431

Unlocks IG88:
Enter the code GIJ989

Unlocks Jango Fett:
Enter the code KLJ897

Unlocks the Vulture Droid:
Enter the code BDC866

Unlock Watto:
Enter the code PLL967

Unlock Zam Wesell:
Enter the code 584HJF

Unlock Zam's Speeder:
Enter the code UUU875

To do this sneaky glitch build two control panels at the begining of Chapter IV, Episode 1. When you have built the control panels go to the left of the room and keep pulling the level and you'll be able to collect as many coins as you want.

Collect the blue glasses that are on the floor in the Cantina in Mos Eisley and stack them together. When you do this a bowling ball will appear which you can 'Force' throw into them to get coins.

If you want to unlock this professor of archaeology and adventurer go through the 'Bonus' doorway in the Cantina at Mos Eisley and then through the a door which is marked 'Trailers'. Watch the trailer for 'Lego Indiana Jones' and you'll then be able to buy him for $50,000 at the shop.