Here are books that were suggested previously, with some commentary:
The Orphan's Tales: In the Night Garden by Catherynne M. Valente - A lot of people sounded interested in this, with the main drawback being the book's length. Either it would be one *hefty* month of reading, or it would need to be spread out over two months.
The Wizard of Oz by L. Frank Baum - Suggested some time previously, seems to be one of those "no one hates it, no one's pounced on it" suggestions thus far.
The Best Short Stories of J. G. Ballard - Suggested somewhat recently, not much to comment on thus far.
The Name of the Wind by Patrick Rothfuss - Suggested somewhat recently, I went ahead and included it just in case, but the consensus seemed to be leaning toward "oh gods, not another non-ended epic fantasy."
Wild Cards edited by G.R.R. Martin - Suggested by me, recently. There seemed to be some interest in this, but the main difficulty (and possibly an insurmountable one for this format) is the fact that it'd be damned hard to get hold of for those who don't already own it.
Unnamed Agatha Christie book - Suggested sometime previously, seemed to be at least some mild interest. Either we could do one of the collections of her short stories, which would work well with the format, or another book. (I myself lean toward The Murder of Roger Ackroyd which might be fun to read as a group.)
The League of Extraordinary Gentlemen volumes 1 and 2 - This was suggested by... me, I believe? Somewhat recently. It might be interesting, and the graphic novel format seems to work well for this type of thing, but a) it'd probably be something for future months if we do it, since we're just wrapping up V for Vendetta, and b) it'd involve buying two books, since the mini-series were 6 volumes each.
The Princess Bride by William Goldman, because dude. Suggested by me last month, didn't really get a chance to get discussed.
And things I'm going to suggest now, along with anything suggested in comments that I'll edit in as well (including if I remember the other book I wanted to suggest then promptly forgot...)
Howl's Moving Castle by Diana Wynne Jones, because a) it's a good book, b) it's not overly long, and c) if we could drum up more participation, it'd be interesting to see how the commentary splits between those who have seen the movie but not read the book, people who have read the book before, people who have done both, and people who have done neither.
Mrs. Frisby and the Rats of N.I.M.H./The Secret of N.I.M.H. by Robert C. O'Brien, for many of the same reasons, although it's been longer since I've read this one (and it's probably more children's book than fantasy, technically).
Unnamed Discworld novel, since we ended up not doing Night Watch for May. (So sorta new suggestion, sorta old.)
Alrighty then! Please discuss, and feel free to make other suggestions, although I realize there isn't as much time to discuss as would be nice (I'll really really try to remember to post the discussion earlier next time, gah!) I'll put a poll up probably in a couple days to finalize the decision, and give people a chance to pick up the next book.