Geomapping with Reilly

Geomapping with Reilly refers to an unmarked and repeatable quest in Fallout 3.

Detailed walkthrough
After completing the quest Reilly's Rangers and offering to assist Reilly with her mapping service, she will give the Lone Wanderer a geomapper module. As long as it remains in one's inventory upon returning to the Ranger compound, Reilly will pay 30 caps per discovered location (maximum of 4,890 caps) upon being spoken to.

Bugs

 * It is possible that you won't get paid for locations you already have the first time you talk to Reilly after she gives you the geomapper module. She will say that the Rangers already know about all of the locations you have and will give you nothing. If this happens, try immediately talking to her again. You can also try dropping the geomapper module and picking it back up, then speaking with Reilly again. If she still won't pay you for the locations you have already discovered, try leaving the Ranger compound and re-entering before speaking to her again. Another alternative is to simply seek out at least one new point of interest and then return.
 * Sometimes, if you talk to Reilly and ask for the caps for the geomapping, she will say that she will give you the caps, but will make her way to her bed to sleep. When you wake her up, she will say that she already has all those locations and will not pay you. This can be fixed by reloading a previous save.
 * Sometimes Reilly will claim the Rangers already know about all of the locations you have and refuse to pay, even if you exhaust all of the options listed in the first bug.