Get Star Map Easily:
On Dantooine in the ruins, instead of fighting the guardian droids, you can ignore them and get to the Star Map. First, have only Bastila in your party. Then when you go into the first door in the ruins, go into solo mode. Bastila will stay behind while you talk to the droid. Talk to it, and go into the proving grounds. Run past the droid and use the console. If you go into combat mode, simply press B to turn it off. Now run into the next room and repeat. The door to the Star Map will be open, and you can go in. Run to the Star Map, still ignoring the droids. After the cutscene, go back to where Bastila was left and turn off solo mode. Then run through the door and you're done on Dantooine. 

Unlimited Security Spikes:
To get unlimited security spikes, you need to have T3-M4 and be on the Ebon Hawk. First, make sure you have no spikes in your inventory. Now, go to T3-M4 and ask him to construct a security spike. Do this until you can't get any more. Now, go to the cargo bay and open one of the Metal Boxes or Plasteel Containers. Put all the spikes you just got into the box. Now go to T3-M4 and repeat the process until you have as many as you need.

Easy Money:
Have Zaalbar make you grenades, T3 make you programming spikes, and Canderous make you stimulants. You can then sell these things to different merchants you encounter.

Hidden Ending: 
(Note: You need two controllers for this trick) 
With your primary controller plugged into ports 1, 2 or 3 have a second controller plugged into port 4. Before you enter the final battle with Darth Malak (do NOT open the door), pull both the 'L' and 'R' buttons on both controllers for a secret ending. 

Voice Modulation 
(Note: You need two controllers for this trick) 
With your primary controller plugged into ports 1, 2 or 3 have a second controller plugged into port 4. While playign the game, press the black or white button on the second controller to raise and lower the pitch of the in-game voices. 

Keep the Sith Armor 
Once you obtain the armor and complete the associated quest, equip it to another party member when you select the option of handing it over. 

Keep the Sandpeople Robes 
Once you obtain the robes and complete the associated quest, equip it to another party member when you select the option of handing it over. 

Easy Path to the Dark Side 
When you discover the stowaway aboard the Ebon Hawk, select the option Get out of here, whoever you are! Right now!! Then, before she leaves, talk to here again and select the same option. Continue to repeat as you gain 1 Dark Side point each time. 

Fun with Bastila's Wardrobe 
Equip Bastila with dark robes and then remove them to see her in slightly different underwear.

Alternate ending sequence:
Reach the final battle with Darth Malak, but do not open the door yet. Press L + R on controllers one and four. 

Change voice pitch:
Hold Black or White on controller four during game play to increase or decrease the pitch of the voice dialogue. 

Increase Dark alignment:
After finding the stowaway on the Ebon Hawk, select the "Get out of here, whoever you are! Right now!" option. Talk to her before she leaves to catch her again. Choose that dialog option again. Repeat this to increase your Dark alignment. 

Hidden level up:
On the first level, when you just get out of the fight with the dark Sith, he gives you a key. It is to the cargo room on your speeder. When you get inside that cargo room, go behind the lightsabers to find a level up

Hidden names:
When using the random name generator, press it enough times and you will get character names from the Homestar Runner cartoons, such as "Homsar" and "Kerreck." It might take a few tries to find these.