Found another great blog entry today, this one's about what to do after you've finished your first draft and the importance of knowing your back-cover blurb before you start editing: http://bloodredpencil.blogspot.com/2009/01/whats-your-story-about.html
Here's the one I wrote for my sci-fi thriller, Waking up Jack Thunder:
Only Special Agent Jack Thunder can identify a CIA traitor and locate $3bn in missing drug money. Trouble is, a failed mission left him in a coma, so the Agency turns to Bobby Newton, a shy scientist whose invention enables comatose patients to communicate with the outside world (secretly using his own brain as a conduit).
All goes well until masked gunmen sabotage the procedure, leaving Bobby for dead. He wakes up to find his patient gone, his lab destroyed, and Thunder’s copied brain patterns stuck inside his head. Not knowing who to trust, Bobby goes on the run. Hunted by the CIA and a ruthless drug baron, his only chance of survival is Jack Thunder himself, who appears at his side like a ghostly holograph that only he can see.
I like to write a rough version of the back-cover blurb between finishing the first, rough, outline and starting the first chapter. That's not to say that I won't make any major changes to the outline after that, but I find it helps me keep the story on track. It's easy to meander off course if you don't have a clear idea where your story's going, on the other hand, there's usually a lot going on that's important too. In the end I guess it's a question of choosing which events/characters to leave out of the blurb completely, rather than which ones to include
You can use the blurb in a query letter too. After all, if it’s meant to interest a potential reader, it ought to interest a potential agent too.
Speaking of agents, I hear it's important to have a one-line pitch sentence (also great for when people ask what your book's about).
For Thunder, I say: 'It's a sci-fi thriller about a shy scientist who gets a copy of a secret agent's brain stuck in his head.' Summing up a story in one sentence is harder than you'd think. I like to practise by making up tag lines for movies and tv shows.
Mr. & Mrs. Smith Action/comedy: The top assassins from opposing agencies just found out they're married... to each other
I Robot A sci-fi thriller: In a world where robots are commonplace, the only guy who doesn't trust them finds out he's right.
Big Bang Theory: A comedy about four socially-inept brainiacs dragged into the real world by the down to earth blonde next-door.
Why not give it a try yourself? Let me know what you come up with.