Grand Turismo

To get 1 million credits:
When you take the licences, press and hold -
UP, DOWN TRIANGLE, CIRCLE

Crash Bandicoot 2: Cortex Strikes Back

FREE 14 LIVES:
Jump 10 times on the baby polar bear on levels 14-15

BOSS WARP
Go to the next or previous boss, press and hold, L1, L2, R1, R2, and triangle when standing in the middle of the warp room

CLEAR GEMS
Level 3. Beat level in the given time, when you go to the bonus, die right away.
This gives you more time.
Levels 17, 21 and 23. Take the death route.

EXTRA LIVES
In the second warp room, go to the barking bear and jump on him until 10 extra lives appear. You can die in this one.