If your going to get a 50 mm prime lens, I really recommend getting a compact macro.  You have a Canon system?  I don't know if Nikon has an equivalent but if they do, it is so worth it.
the 50 mm prime is about $50-70 and unfortunately, the 50mm compact macro is about $230(?) but it is an amazing lens.  Super sharp and you can do so much with it.