Anybody else here run across the perfectly beautiful but dead girl "Sweet Jane" in the sewers under New Vegas ? There has got to be some story about her, why she's there, how she got there ! Anybody got anything ?? I kept wanting to revive her, but it was beyond me

You could ask in the Spoiler section.

You mean Sweet Jill.
But there's no info about her, other than being one of the bodies to find a key that starts a little quest.