The Hitchhiker's Guide To the Galaxy.
Why?
Because 5 years ago I realized in a few conversations with various people that I had no idea what they were talking about, and I decided that this book must be common knowledge if so many people know it. So I figured I didn't want to die stupid and set out to read the book. But since in Austria english books are hard to come by, I did a google search and right away I found a .LIT file I could download and read on my brand-new PocketPC I got back then.
My first eBook
It took me a while to figure out that I actually downloaded something from the darknet ... I was amazed that people buy paper books but the electronic ones are free
That got the ball rolling, ever since then I never go to sleep without reading a book, and I have not opened a pBook since.