I have to agree with Michelle (above) about the Harry Potter books! At the time, I didn't step too much out of my familiar genres but a friend recommended them to me. I went to town and bought the first one in PB, read it in one night and went back the next day for books 2 and 3.
That started the obsession. I went to the midnight release parties for books 4-7 and even bought British editions of the books when my mom and I took a vacation to London. And, yes, I also took pictures at King's Cross Station where Platform 9 3/4 should be!