I started reading Sister Carrie a few days ago. You can read it online via hypertext courtesy of the University of Virginia. I purchased my copy with a gift card at Books a Million.
While looking for my next book to read, I searched the web for "classic novels" several times and this book by Theodore Dreiser kept coming back in the search results. It took a few minutes to adjust to the phrasing and style that dates back to 1899, but I'm enjoying it a lot.
I've finished the first seven chapters. I realize it's early, but at this point I'm surprised that the book was considered controversial