I remember there being a lot of freaky-seeming coincidences over the course of our reading it. The one that sticks with me is when we had a long, deep discussion of the significance of keys sparked by the Alexander Keyes ad Bloom is designing, and a student from an earlier class entered the room looking for his lost keys. We all laughed and freaked out; some of us actually screamed. Someone accused our prof of setting it up. The student was stunned. Then there was the time we were approximating how much money Stephen spent over the course of the day & someone out in the quad started playing Pink Floyd's "Money" loud enough for us to hear. I know there were more, but I can't remember them (jeez, it's 22 years ago now!).
A huge percentage of the book flew over my head, and a lot of it still does, all these years and 6 full reads later. I really felt the characters though, and the verbal pyrotechnics are completely amazing. Not until my fourth read through it did I begin to comprehend the book as a unified whole, rather than a series of episodes. There are more priceless moments in it than I can count.
Two years ago I assembled a group of high school students to read the book aloud every week. I've kept my notes on those crazy meetings - a gazillion in-jokes resulted - & someday I'll write something about that. Maybe next year ;)