1) Go to the cheese shops. Obviously this is a plus if you like cheese, but it's a neat experience either way. I ate more Gouda in a day than I had had in a lifetime prior to that.
2) Van Gogh museum. This has been said by others, and I agree.
3) Anne Franke museum. Also said by others, and I too agree.
4) Restaurants. There are a lot of great traditional restaurants. Italian, Middle Eastern, Indian, etc. I had some of the best times just having a nice casual dinner with friends sitting out in the plaza.
5) Canal tour. I didn't actually do this, but it seems reasonable enough.
6) Visit Jordaan. A fun area. I didn't do a lot in Jordaan, but I took some time out for coffee at a cafe, lunch, etc. Again, find some time to relax and just enjoy the scenery.
7) Orchestra. If you're into the arts they have a wonderful orchestra. I was able to see Toccata and Fugue in D Minor with the orchestra rather than organ. Great time.
8) Red light district. You might as well see it. Don't stare too much, don't take pictures, and avoid certain "women" (read: transvestites).
9) Coffee shop. This is where you buy weed from a menu. As someone else said, you'll find mostly American tourists. You might as well at least go check it out, have a drink, and talk with some high Americans.
That's all I can think of at the moment. I love Amsterdam. The people are wonderful in my opinion.