Could always take a look at fallen earth. That's probably as close to a fallout MMO you can get at the moment.It was fun to play, enjoyed the story and leveling, but with other games around and it STILL being the same sword&magic MMO and me having wow for that...well...not really worth it.
When they bring out a good sci-fi MMO, cyberpunk/fallout/whatnot and leave out the "sword&magic in different wrapping", i'll switch.