I was sitting around last night watching the Movie Fallen, and I realized that the ending of it could be adapted to a very interesting fic.
http://imdb.com/title/tt0119099/

The relivent bits from the movie for adapting.

For those who havent seen the movie, it begins showing the main character on the ground dying, and in the main characters voice says "I'm going to tell you a story about the day I almost died" The story is about a fallen angel that is cursed to live without a body, and hops from one body to another via touch. Without boring you with to many of the movies details that aren't relivent to the plot bunny, at the end of the movie the main character gets the fallen angel who is possessing a friend of his, to come out into the wilderness and he disables the car the angel came in, and shoots him. Now normally this would be very foolish, but the main characters idea for stopping the angel is to poison himself. So when the body the angel is inhabiting dies, it has no safe place to flee to, and is therefore destroyed. Needless to say, the body the angel is in dies, and so does the main character. Shortly after that a small tabby cat walks past the screen, and you hear a voice say. "I told you, I was going to tell you a story about the day I "almost died" Meaning the angel possessed the cat to survive and the storyteller was in fact the villian and not the hero.

Now, im not suggesting that the writer make voldemort a fallen angel or anything of a sort, however we dont know that much about how horcrux's work. One could say that while a horcrux excists the body can excist incorporeal, however it needs to possess a body in order to refresh it's energy. Possilby feed of the soul of the possessed, whatever you like. Now that being said, here is the plot bunny itself based on the above. Harry comes to the following conclusions.

1.) There is no way in the time alotted he can gain enough skill to defeat voldemort in a duel.

2.) He is unable to find all of the horcrux's. (Kill off hermoine and you pretty much assure this, but hey it's your story.) You can have him hunt the horcrux's for a while before he comes to this conclusion, kill off a few of your more hated characters, and generally have a blast while he comes to this realization.

3.) Harry comes to believe that the power he knows not, is the fact he "loves" (vomit) his friends enough to sacrifice himself to kill voldemort. Whereas Voldemort is so afraid of death that he would never consider it.

So therefore he comes up with a way to lure Voldemort into a secluded location, and sacrifice himself to kill both of them with nowhere for Voldemort's soul to flee. If this ploy works is entirely up to you, altho it would be nice to see a villian win at the end of a story.

Edit: IMDB link