Courtesy of http://bioshock.wikia.com/wiki/Power_to_the_PeopleNeptune's Bounty
Freezer Bottom Floor: Go through Fontaine Fisheries (where Peach Wilkins asked for the three Spider Splicer pictures). As the player goes down the stairs from the second floor to the first they should see the machine right in front of them.Arcadia
Tree Farm: On the way to the Farmer's Market, it'll be on one's left.Farmer's Market
Winery Cellar Bottom Floor: Take the stairs from the top floor to the bottom floor, and keep going straight once done descending the stairs. The machine should be right in front of the player in the water.Fort Frolic
Le Marquis D'Epoque: Start from the Circus of Values machine in the Lower Atrium. With one's back to the machine, go down the stairs into the Southern Mall. Make a right at the end towards the Gene Bank, then make a left and a quick right, then another left and another right to go into Le Marquis D'Epoque. Go straight upon entering and go down the stairs. The player will see a U-Invent machine in front of them. Go right and then turn right, go straight and then make a quick left to see a room filled with cigars along with the Power to the People machine.
Sinclair Spirits: Once one enters the room, turn left. One should see water falling from the ceiling with a door behind it. To open this door, go to the counter on the opposite side of the room, and there should be a button behind the counter. Press it to open up the door, then go downstairs and the machine should be right there. Upon using this Power to the People machine, all the "statues" will come alive and attack the player. These Plastered Splicers do not make any sound or scream dialogue like most Splicers. They attack the player in complete silence, so keep a watchful eye, as they also never stop spawning and while providing a steady supply of items, can be deadly when exploring. It might be helpful to use this machine near the end of the level to avoid most of them.Hephaestus
Hephaestus Core: Right across from the Gatherer's Garden, on the southwest corner of the core.
Kyburz' Office: In the back of the room on the north side.Olympus Heights
Mercury Suites: In the main square opposite side of the elevator's doors, on the center pillar.
Sander Cohen's Apartment: This is the room where the player gets the achievement/trophy for entering Sander Cohen's personal quarters.
Note: The player must let Cohen live when he was in Fort Frolic to be able to get into this room, otherwise it will be locked, and they will not be able to access the machine. Sander Cohen's apartment can be seen at the lower left of the corner of the map, on the west side square. Basically, go into Cohen's apartment on the first floor, and if the player disrupts the dancers (such as by knocking over the gramophone or killing the dancers), Cohen will come down from his private quarters and open the door for the player. Through the door, at the top of the stairs, turn left and the player will see the machine right there.Apollo Square
Hestia Chambers Fourth Floor: To get to the fourth floor, the player needs to go to the top of the staircase. Enter the room on the right and one should be in Atlas' headquarters. There will be a machine in the second room.
Atrium: The machine is right next to the Big Daddy corpse on the south side of the Atrium.
Optimized Eugenics: The machine is right next to the Gene Bank in Eugenics Analysis.