nikon 50mm f/1.8 light, inexpensive and sharp.
nikon 105mm f/2.8
try some manual lens as well ... old nikon manual lens prices drop quick, but they are built to last forever (metal body) with superior optical performance.
http://www.nikonians.org/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=5987&forum=DCForumID6