Why not go over to Fallout3Nexus and have a look for yourself first to see if any additional mods strike your fancy? To me it is a bit redundant to ask which mods one would 'need' as this is different for each person. At present time there are simply tons of mods out there waiting to be tried out, and you're not really providing people with what you're actually looking for in a mod.
So check up on the project/release threads on these forums or Nexus and try out the mods you think would add to your gaming experience
Greetz,
Milt