I'm not interested in the first sentence so much as I am in the first paragraph or thought. I agree with Lyda that you have to hook the reader quickly, but I'm willing to take a little longer to do that, call it the first ten lines of text. Now, last sentences. . .those are very important to me, but not really something that can be talked about without spoilers. I do have a few pieces around with a punchy short first line or couple of lines that seem appropriate to the discussion:
The beverage was coffee, not java, not cappuccino, just coffee. My only companion was my avatar, Harvey.
This is a short forthcoming in Absolute Magnitude and what I like about is the way it establishes character and (with the next couple of sentences) the idea of cyber setting.
"Nothing here," said Melchior, his voice echoing from the depths of an ancient citrus-wood chest.
"Keep looking," I called back to my familiar, yanking another drawer from my many times great-aunt's desk
What I like about this is the sense of urgency, of distorted family relations, and of unanswered questions.
Who says you can't teach an old dog new tricks? The eyes of Cerberus glared down at me, six balls of black fire. There was no dog older or more dangerous. But here I was standing practically in his mouths, trick in hand.
This is the sequel to WebMage and I love the image of Cerberus playing bridge and what that tells you about the kind of person who would play with him. It gives the reader the setting of Hades, a risk taking protagonist, and silliness.
The Black School:
When Adair was eight they came for his cousin Dougal. They took him right out of class and whisked him away to the Royal Edinburgh Academy of Sorcery. That was its name, but no one called it that. They called it the Black School
This is the book I'm working on right now, and what I like about it is the darkness starts with the first sentence, the sense of powerful and dangerous forces. It also gives the Scottish setting.
Winter of Discontent:
Act one. Scene one.
A theater. Red light from the exit signs provides the only illumination. A lone man, barely visible in the darkness, paces haltingly back and forth across the stage. He begins to recite, hitting some of the lines with special emphasis:
This is a novel that's currently out looking for a home. I like this opening, but I think it's an example of a very slow burning start. You need to read a full four or five paragraphs past this to get the full effect, but that's not necessarily bad. This is a very cerebral book, and a starter's gun start would be inappropriate.