The other day I received a couple of goodies from my wishlist (thanks to David Costa) in return for fixing an SQLite bug. One of the items was I Am Legend.
If you are a fan of vampire stories, or even if you're not, this is an excellent short story (just shy of 160 pages of very readable type). It was so good that it only took me a few hours to read, and as I approached the end of the book I got the "oh no! the story is almost over" feeling that accompanies books of this calibre.
I thoroughly enjoyed the book. If you're not a vampire fan, don't be put off by the frightening cover artwork--the story is not particularly violent or explicit, making excellent use of mood and tension instead.