Heart of Ravenclaw - something focusing on, in my opinion, Rowena Ravenclaw
Deathly Hallows - stumps me... yet this is the one she choses? gah....
Deadly Veil - *giggles* just plain obvious.... lol the veil could be a horcrux, i saw someone mention that somewhere on SS a bit ago
Demon's Sword - Voldy = Demon so Voldy's sword. unless the trio faces something else, more demon-like....
Quest of the Serpent - something to do with slytherin obviously looking for something of Slytherin's
Grey Lady - hmm.... i'm not getting any ideas for this one, confused
Heir of Gryffindor - eh? this is kinda confusing... it will involve going to somewhere or someone that is the heir of Gryffindor.... finding something they have, horcrux! lol
Lost Sceptre - almost duh again, a very old, very ancient, very thought to be lost sceptre will be found and be a horcrux... lol
Broken Wand - somebody's wand will get broken
Gryffindor Quest - yet again almost obvious, Ron Harry and Hermione are all Gryffs.
Peverell Quest - hmm... Peverell is a place, so this one stumps me.... unless Voldy sent a horcrux of some kind there were Harry wouldn't EVER think to look
Wand of Gryffindor - Harry's wand, almost obviously
Ring of Destiny - obviously, something about the ring that turned Dumbly's hand black.
Elder Wand - okay this one i dunno... umm... Dumbledore's wand? Tom Riddles wand? someone dead i'm guessing, their wand will play an important role.
Revenge of Dumbledore - eh? hmm... wisedom from his portrait i'm guessing
March of the Death Eaters - duh.
Return of the Dark Lord - duh.
Curse of Nagini - haha the snake is a horcrux
Last Prophecy - duh.
Hallows of Hogwarts - obviously again.... Hogwarts
Mudblood Revolt - Hermione is involved
Seventh Horcrux - obviously...
Wand of Grindelwald - means that Grindelwald will be important.
Final Curse - means that harry will die.
there. my ideas of what ALL the other possible titles mean. just more clues as of what is in book 7.