While ammonium triiodide [aka nitrogen triiodide] is not the bane of one's existance and can probably be made by a knowledgeable person with moderate lab experience and only standard safety equipment, it is still a dangerous substance. Given my experience (yes, I have seen and worked with this stuff), I wouldn't go quite as far as jdurg, because I don't feel that it has quite the danger that NG does, but I would also not dance and laugh around the safety issues.
Interestingly, I also did this in HS, under the close supervision of my teacher, although I would not speak of this material as cavalierly as chemicaldream. This substance is a brownish paste and is so unstable that the air movement from the fume hood set it off from time to time. It explodes with a sharp cracking sound and releases a large cloud of iodine gas. This is not something to be done at home. If you make it in a fume hood with experienced personnel, as it seems chemicaldream did, then you're probably OK. If you're an idiot and make more than a couple hundred milligrams, you're going to have some trouble; this material is a high explosive and will tend to break things around it if in sufficient quantity. Especially if it's resting on a glass funnel to dry or something like that, you're in for some glass shrapnel.
Although it seems that chemicaldream may have done this safely, I would not say that it was safe for him/her to have touched the crystals with his/her hand. If his teachers allowed him to do this, it was probably poor judgement.
Chemicaldream, your attitude is not appreciated; a belligerent, almost careless attitude toward other posters is rude. Taunting others by asking if they are afraid of a balloon popping is unacceptable. Please treat others with more respect, and respect the wishes of the admins when it comes to posting preparations of explosives and other dangerous materials. Not adhering to this will get your account banned. If you wish to pursue such inquiries, try directing your requests to alt.engr.explosives, a newsgroup devoted to such matters. You can find it on the google groups.
One last note: Scratch, this is not a good explosive to work with for your picture taking. It is so unstable that it would most likely explode while setting it up, thus not allowing you to get a picture anyway.