Fallout 3 used Mad Max's concept of Raiders and so did Tupac.
And if you mean rapping raiders then... ugh...
If I see one person rapping in freakin' fallout then I'll break that game's disc into a million little pieces and never buy another fallout game again.
Rap in fallout would be a big slap in the face to the lore and it's fans. (IMO)
oh no no, nevermind the rap and dance-floor bits, but the rest of it: Organized gangs (although you shouldn't be able to tell them apart in the game, or be able to join any of them, as they'd all just bust you up on sight equally bad, but you could exploits the conflict between them, like luring different groups into each other) along with their eccentric leaders (to add more color to the cast,) freaky members (not all just nameless underlings with no dialog,) and of course:
Vehicles! vroom vroom!