I use the 85/1.8 AF most of the time on my N90. The autofocus became very helpful to me as my baby started moving!

Another favorite of mine is the 100/2.8 series E lens. I use this on an old FE. Small, light, but very good optically.

I also have the 80-200/f2.8. Nice toy, but it doesn't focus closer than 6'. Both the 85mm and the 100/series E focus to 3', which is handy indoors. Also, the zoom is huge.