Portal 2 Cheats

Lunacy (20): That just happened
Narbacular Drop (25): Place a portal under your co-op partner while they are gesturing
No Hard Feelings (10): Save a turret from redemption
Obstacle Building (15): Complete all test chambers in the Excursion Funnels co-op course
Overclocker (30): Complete Test Chamber 10 in 70 seconds
Party of Three (25): Find the hidden companion cube in co-op test chamber
Pit Boss (30): Show that pit who's boss
Portal Conservation Society (20): Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
Portrait of a Lady (10): Find a hidden portrait
Preservation of Mass (20): Break the rules in Test Chamber 07
Professor Portal (75): After completing co-op, complete Calibration Course online with a friend who hasn’t played before
Pturretdactyl (5): Use an Aerial Faith Plate to launch a turret
Rock Portal Scissors (20): Win 3 co-op games of rock-paper-scissors in a row
SaBOTour (10): Make a break for it
Scanned Alone (5): Stand in a defective turret detector
Schrodinger's Catch (20): Catch a blue-painted box before it touches the ground
Ship Overboard (10): Discover the missing experiment
Smash TV (75): Break 11 test chamber monitors
Stalemate Associate (15): Press the button!
Still Alive (15): Complete Course 4 with neither you nor your co-op partner dying
Stranger Than Friction (15): Master the Propulsion Gel
Tater Tote (15): Carry science forward
Team Building (10): Complete all test chambers in the Team Building co-op course
The Part Where He Kills You (20): This is that part
Triple Crown (15): Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
Tunnel of Funnel (15): Master the Excursion Funnel
Undiscouraged (10): Complete the first Thermal Discouragement Beam test
Vertically Unchallenged (15): Master the Repulsion Gel
Wake Up Call (5): Survive the manual override
White Out (15): Complete the first Conversion Gel test
You Made Your Point (10): Refuse to solve the first test in Chapter 8
You Monster (5): Reunite with GLaDOS
You Saved Science (100): Complete all test chambers in all courses of co-op

Alternate Title Screen
Beat the game for an alternate opening screen.

Singing Turrets
In one of the test chambers, you will see a turret in a ventilation shaft at the very beginning. If you use the laser and reflector cube to destroy it and go through the new opening, you can find some turrets rehearsing a song.