During the game press Select to bring up your inventory screen. Highlight the Timex and hold:

Up + R1 + L1 + L2 + Circle then press Triangle.

Your ammo will now be unlimited as well as your Medikits. While in the game, press SELECT to bring up your inventory. Then highlight your Timex and hold:

Down+R1+R2+L1+L2+CIRCLE and then press TRIANGLE.

Then exit the game to find a "Special Features" menu on the main screen. From there you can view storyboards and concept art for the Next Generation Tomb Raider game as well as a pre-rendered (as in NOT realtime) video of what the game may look like.

During the game press Select to bring up your inventory screen. Highlight the Timex and hold:

Down + R1 + L1 + L2 + R2 then press Triangle.

While at the main menu highlight the New Game option and press and hold:

L1 + Up

While holding those two button press the X button. You'll start at the Russian Base.

While at the main menu highlight the New Game option and press and hold:

L2 + Up

While holding those two button press the X button. You'll start at the Black Isle.

While at the main menu highlight the New Game option and press and hold:

R1 + Up

While holding those two button press the X button. You'll start at the Tower Block stage.