Roadside Picnic, by Arkady and Boris Strugatsky
I first read this book a few years ago when Ekaterina recommended it on her blog. But the edition I read was the old translation from the 70's, and I wanted to read the newer translation from a couple of years ago. It said it fixed some errors and put in more material, and it also had an afterword explaining the history of the novel's publication in Russia (which is pretty fascinating all on its own).
Red Schuhart is your average schmo. He's a stalker-- he ventures into the Zone to retrieve artifacts. It's a very dangerous occupation; the Zone is an area filled with random alien objects. There are five of them on the earth, rather as though somebody had thrown some trash out of the car window on their way to somewhere else. The purposes of the different artifacts are unknown, and they are often extremely dangerous. Those who venture into the Zone and survive are somehow changed; their children are not quite human.
Roadside Picnic is a true classic of science fiction; it inspired a movie, a video game series, and a sport. Well, it's not exactly a sport--it's the Russian pastime of sneaking into derelict buildings for exploration.
I was really happy to be able to read the new translation, which is more detailed. It still has the same feel, but there's a bit more to it. And it's a great book.