About 3 weeks ago i bought myself a second hand Nikor AF 50mm f1.8 D.
It came with a HS-9 Metal Lenshood and a Hoya Super Pro1 52mm UVfilter.
I was walking around with a moderate zoom lens since i bought the D90. So it was at first difficult getting used to using the zoom in my feet or backing up because i was to close. But i wanted to learn the use of a prime. The DOF/Bokeh it promised me was a real surprise. Getting a nice bokeh with the 18-105 was possible but with this prime it is amazing. Besides, it is way sharper from roughly f2.8 and up. So i am still in a steep learning curve but i think i am getting the first results i am looking for.
(lens picture is taken from the web)