edisoncarter at GTASanAndreas.net has recently been finding new cheat codes by "wiring up a game pad to a PC's parallel port using optocouplers". Yes it's highly complex.
But the controls are like flying a normal plane.
Square, Down, L2, Up, L1, Circle, Up, X, Left
Fast/Rare cars appear regularly
Up, L1, R1, Up, Right, Up, X, L2, X, L1
Full Weapon Aiming Whilst Driving
Aim and shoot at passing pedestrians/vehicles, as your gang would do whilst in a car
Up, Up, Square, L2, Right, X, R1, Down, R2, Circle
All taxis have nitrous and bunny hops
Horn to bunny hop
Up, X, Triangle, X, Triangle, X, Square, R2, Right
Spawn a Bulldozer
R2, L1, L1, Right, Right, Up, Up, L1, Left
Very few cars on the streets and no pedestrians
X, Down, Up, R2, Down, Triangle, L1, Triangle, Left
This cheat freezes the clock at 21:00 after a rapid whether change the skies will be orange.
Left, Left, L2, R1, Right, Square, Square, L1, L2, X
Gangs Control the City
This cheat will empty the streets leaving just gang members and vehicles within the gang territories
L2, Up, R1, R1, Left, R1, R1, R2, Right, Down
Infinite Lung Capacity
Now you will never drown
Down, Left, L1, Down, Down, R2, Down, L2, Down
The cheats page will be updated shortly with these new codes.