I am writing to you because she said you listen and understand and didn't try to sleep with that person at that party even though you could have.
That's how it starts, so that's how this community starts.
I'm thinking it's very likely that The Perks of Being a Wallflower is in production as an MTV film, and since Chbosky is a screenwriter I would expect him to have written the screenplay, but I actually took a whack at writing a screenplay based on the book. I've got about 30 pages so far. It's a useful exercise, but I don't imagine they would need an adaptation by anyone other than Chbosky, so it's really just for practice.
I had the idea to give the book to someone as a series of letters as if they were written by Charlie, and even including the mix tapes and assigned books mentioned in the story, but I'm afraid someone might find that kind of thing a bit too weird and stalkery. Too bad, really, because it's something that could also be taken as a very romantic gesture.