Tokina ATX 80-200mm f/2.8 in manual focus is a great lens--used one for 2 years before I "upgraded" to auto focus for photojournalism.

If you want a smaller lens the 75-150mm Nikon zoom is well spoken of, but I have never used this one.

If you don't absolutley need the zoom, you can do great things with any one of the 180mm f/2.8 Nikon incarnations.