Added a few more instrument tags. Lesser known/hard to spot ones: The thing behind the cello is a marimba. The clicky things that flamenco dancers use (seen on the beige box to the left of the french horn) are castanets. You guys need more cowbell, because there's one between the bassoon and bongos.
I didn't tag each and every instrument when I went through the first time. The reason being that Danbooru is not an instrument site; I figured it probably had little use for new random rare instrument tags.
I tried only to use tags that already existed in the system (I did do a search for castanets at the time). I suppose there are so many meaningless 1 post tags out there already, so adding a few more isn't going to hurt much, but that's why there were some untagged instruments.
That instrument you call a bassoon near the cowbell is not a bassoon. I'm not really sure what it is, but I think it might be one of the lower pitched cornamuse... (http://en.wikipedia.org/wiki/Cornamuse and http://www.tands.pl/images/foto/Cornamuse-B.jpg) Though it still doesn't quite look like a bass cornamuse either... I say that it is not a bassoon because bassoons are double barrel instruments, so they curve around themselves and the bocal (curvy metal part) doesn't come out of the top. They also have a bell that sticks out at top, and not nearly so much at the bottom. (http://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Bassoon_1870.jpg/800px-Bassoon_1870.jpg) Since the artist did such a wonderful and accurate job on all of the instruments, I don't think they would have done that poorly on the bassoon ^ ^;; Hope I was helpful!
OH and the J-shaped instruments to the left of the banjo are called crumhorns. (http://en.wikipedia.org/wiki/Crumhorn) I've heard a recording of one before, they sound TERRIBLE.
