I bought that 50mm f1.8 AF D lens that LahLahSr suggested and it worked great for basketball season. I shot basketball with it mostly at 2.2, as the D90 seemed pretty comfortable and quite accurate with the af at that f-stop, and was able to shoot most everything at 1/320s or better, and around 1800-2400 iso. I actually had a photographer friend change from his 85mm to a 50mm, as he liked the shots that I was getting with the 50 better than what he was getting with the 85 1.2. Toward the end of the year at some tourneys, I played around with the 50mm and a 1.4 tamron AF tc, and with some exposure compensation, it actually worked a lot better than I expected. I hated the combo when I first tried it, but went back to it a few times and figured out the quirks, and it ended up being quite usable in certain situations.
This last basketball season was such a wonderful and intriguing learning experience for me!! It really forced me to quickly learn the quirks of the D90, and what focus points and focus modes worked best, and how to anticipate and accurately frame quick moving subjects. By the end of the season, I was also playing around more with manual focus, as I started to trust my eyes again.
I ended up selling about $300($180 in profit) worth of my sports photos, which easily paid for my smugmug pro subscription and gas money to the playoffs....so that worked out well.
Some other dirt cheap lenses that I picked up....60mm micro Nikkor manual focus and a very dirt cheap tamron 28-200 ld if af....just for giggles. I also found a Vivitar 2x macro tc for real cheap. I had that same tc with my Minolta, and it was a very versatile tc for macro work, as it mimics extension tubes to a certain extent.
Have also thought about getting one of the older Vivitar primes in the 400mm range......something in a t mount, as you can get those for less than 40 bucks, and would probably be fun for moon shots.
I went nuts with lenses with my old Minolta, and I am finding that I am doing the same thing with the D90.....lol. One of the main reasons why I bought the D90, since it can use the older AF stuff.
I also picked up an old, in mint condition, Nikon N90S for around 40 bucks, just to shoot film every once in awhile so I don't get too lazy in my habits with the D90....easy to do with digital, imo. Already shot a test roll on the N90s, and it's a wonderful camera, too.
Have also been looking at the Vivitar 383 flash unit. My SB28 works fine in manual mode on the D90, and the N90s loves the SB28, but I wanted something at a reasonable price that would do TTL on the D90, and I have seen good things about the Vivitar 383. Anyone have any experience with it? I don't do enough external flash work to justify the cost of a sb600-900. Plus, I have some wein slave units for when I used to use my old Canon S-3 with external flash, so might be fun to experiment with the 383 and the SB28 in a dual flash setup.
Anyways, sorry I rambled so much......I sure love being back into SLRs, again!!! I don't post here often enough, as you all always offer such good advice and opinions for the most part.
I have all my sports shots over on my smugmug site, now.....but I have some junk family and friend shots, and some test shots with the Tamron 200-400 if anyone is interested.