It's funny, but what might be the most famous scene from Glengarry Glen Ross isn't a part of the stage show. Mamet added the Alec Baldwin character specifically for the movie, and it ended up being the scene everyone remembers. Here's a nice little (NSFW) send-up (link via Ken Levine.)
Directing this show for Dreamwell is easily among my list of favorite things I've done in the theatre. (The only thing I would rank higher was acting as Mr. Peachum in Threepenny. Being Elwood Dodd in Harvey rounds out my top three.) The cast was great, a true all-star team, and it was a blast to work with them and watch them and help them (not that they needed it). Here's a link to some photos from the production.