The Sigma 70-200 f2.8 macro. It is a GREAT portrait lens, and with a constant f/2.8 aperture its GREAT in low light situations when you are trying to capture action.
I also use a Nikkor 24-85 f/2.8-3.5 a lot. Its another great lens that is fast and a good all around lens.
And then if you REALLY want a nice lens, a 50mm f/1.8 or 1.4 is a GREAT prime lens often referred to as the 'nifty fifty' because it is so versatile.
fyi... if you want to see an example of my work,
www.imagesbychristophercoy.com Most everything in my galleries was shot with the 24-85.