More:Fallout 3: Quests

From GameWinners

Contents 1 The Replicated Man quest: Get both rewards 2 Shoot Em In The Head quest: Rigged election

The Replicated Man quest: Get both rewards

• When you discover the identification of the android and are deciding to turn him in or warn him, go to the android first. Convince him to go to Zimmer on his own and he will reward you. After that, go to Zimmer in the science lab. Tell him about the android's identity. He will also reward you. Note: You will still get bad karma.
  

• You can get both rewards if you go to Harkness (the android) first and agree to help him. One option when you agree to help him is gaining permission to kill Dr Zimmer and his bodyguard. You will get the plasma rifle from Harkness and then can go to the science lab. At that point you can betray Harkness and tell Zimmer his identity. You will then gain the VATS Perk from Zimmer. When Zimmer attempts to leave to look for Harkness, you can still kill him and his bodyguard with no penalty from the locals. When you return to Harkness he is none the wiser, and acknowledges that you have killed Zimmer. By doing this you will get both rewards and Harkness remains in Rivet City.
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Shoot Em In The Head quest: Rigged election

When on the "Shoot Em In The Head" side quest in the Republic of Dave, win the Speech challenges to be get the key and be allowed to stay. Ask Dave if there is anything to do to help with the elections. He will ask you to get everyone to vote. Go to Bob and Rosie and get them to run for President. Get everyone to vote. Inform Dave you are finished then run to the ballot box and hide behind it. It is locked but keep pressing on it until Dave comes to open it. You will see the ballots. You can now rig the election.