From a quick browse, it looks like 99% of the books mentioned in this forum are of the non-fiction variety. I've always been impressed with the impact that well-written fiction can have on someone's life. I clearly remember four books I've read that focused on issues of immortality:
1. The First Immortal by James Halperin: One we're all familiar with, which gives a good look at what cryonics holds.
2. Diaspora by Greg Egan: One of my favorite all-time books, which really helped me think about what the implications of immortality truly are. Fascinating book that explores a variety of issues, but it does an excellent job of showing the massive scope required to think about what it'd truly be like to live forever.
3. ____________. I can't remember the name of this one, but the story went like this: They could replace all the organs in your body and make you "new again", but the procedure cost $1,000,000 and you had to have it done every 10 years. And, if you were rich, you had to give ALL your money to the medical organization. In essence, you could buy immortality -- but you had to start anew every year. Anyone know the name of this (published in '81, I think)? The protagonist discovers that the 10 year time limit isn't necessary, and is an artificial creation to prevent wealth accumulation...
4. The Experiment by John Darnton. A typical "you have a clone" novel, but the life-extension themes are much heavier here than in other similar novels (like Chromosome 6 by Robin Cook). It raises the interesting question: What would you have done if you were born 50 years ago and devoted to life extension?
Any others out there where immortality / life extension play a central theme? Give a link and a description!