The code is on the door of the sauna, the code is 1540. It has Money, Drill Fuel and the audio diary "Fitness" inside

The code is located on a newspaper in the Fishbowl Diner, the code is 0047. The door must be opened in order to progress.

The code is on the Audio Dialogue "The Date is the Code", the code is 1919. The door must be opened in order to progress.

The code is on the Audio dialogue "A Gift from Billy", the code is 1080. Once opened, you will have acces to a Power to the People machine.

The code is on the wall by the tied corpse in the Plasmid showroom, the code is 5254. There is Careful Hacker 2, money, bandages and ammo inside.

The code is on the Audio logs "First Two Digits, Last Two Digits and on the eall near a toilet tank in the Holding Wing, the code is 2673. The door must be opened in order to progress.

The code is on the audio logs "Legs", "Mouths", "Arms" and "Eyes" as well as on the recreational therapy room wall, the code is 4146. Inside there is a First Aid Kit, EVE Hypo, money, and rare ammunition.

The code is on the audio log "The Books are the Code" and is on the bookshelf in Reed Wahl's office, the code is 2341. Inside there is a Safe (containing money, Shells, and Mini-Turrets), access to the Master Input Console (to hack the beacon).

All of the credit goes to http://bioshock.wikia.com/wiki/Codes since all the information came straight from there! I hope this helps!