Nikon D5100 recommendation for extra lens beside kit 18-55?

I bought recently a Nikon D5100 with kit lens (18-55mm), and would like to have some indications on to which other lens I could buy. I'm more interested in street photograph, landscapes and portraits (parties, outing with friends etc). Try to keep options and value as low as possible.

A "nifty fifty" 50mm f/1.8 for about $220: http://www.nikonusa.com/...F1.8G.html

18-200 mm is a good one lens solution

Here is your problem.

The 18-55 mm is just the lens you need to shoot what you want.

The alternative is the 17-55 mm f/2.8 lens, however it costs $1, 540, do you really want to go there?

Basically these are the specific lenses you would be using if you had deep pockets

Street photography: 17-35 mm
Landscape: 10-24 mm
Portraits: 50 mm
Parties: 24-70 mm
Outings with friends: 18-200 mm