One way to reduce poly-count: Well, say you have two poly spheres. They are positioned so they intersect. There are many polygons inside the structure that you cannot see obviously, so it would be a good thing to get rid of them. Select one of the spheres, Then hold down shift and select the second sphere. In the modeling menu, choose Polygons>Booleans>Union. This joins both spheres where they intersect and eliminate all inside polygons that you cannot see when the spheres are shaded. This is something I just learned, too, thanks to Kbrown and Roman. The only drawback is that you usually have to delete the history of both objects before and after you do the boolean. It also cannot work on nurbs. You can always convert nurbs into polygons, though - select the nurbs object and choose Modify>Convert>Nurbs to polygons. This usually shoots the poly-count way up, though, so it's no help to you.