Six Characters in Search of an Author, The Island by Athol Fugard, The House of Bernarda Albe (The original Lorca, not the Lachuisa Musical adaptation), hey why not those classic old Greek chestnuts... Medea, The Persians, Oedepus Rex, The Bacchae? The advantage of these texts is that almost anything goes. In essence, what I'm trying to say is that any Straight Play text can be finessed into a black box, and classic texts practically beg for that subversion. (As a caveat, I'm a grad student in theatre, and I just finished a semester where we had to "create a performance volume" a week for a wide variety of texts, so if you need more suggestions, pm me.)
The one show everyone on Broadway is waiting to see: Twyla Tharp presents: Big Bottom - The Spinal Tap Jukebox musical!