Hub: Police Station, Foundry in Old Town, Tanner in Old Town, Kali Kalune near Northern Entrance, left side building. (4)
Junktown: Casino Boss, Helmet buyer in Tent in middle of town, right side, Raider Gear in tent near southern entrance, right side. (3)
NCR: Tent behind the exterior vendor near entrance, Condom buyer on far left near pens, Ratchet takes Junk, (3)
San Francisco: Numerous. Maybe like 5. Talk to Ban Chao, and explore the town.
L.A: Girl in one of the tents on the right side, and opposite of that, there's another guy. (2)
There might be more but I forget. Have fun.