This is the 1st round of at least 2 rounds (and up to 4 rounds if sufficient interest is generated). So in the immortal words of Timothy Leary "Turn on, tune in, and drop out."
The list is a great blend of popular mainstream works and works that might be described as belonging to the counterculture.
For younger people there are graphic novels and lots of YA books including the Harry Potter series. SF fans are very well catered for. In fact this challenge has cult books from every genre, including horror, fantasy, romance, adventure, dystopian worlds, mystery, classics and politics, with a definite emphasis on alternative lifestyles.
BTW, you needn't bother looking for any fresh challenges (or even stale ones) from me until the New Year overload diminishes.