I track the books I've read and want to read on Goodreads (https://www.goodreads.com). I currently have about 200 books on my "to read list". I find interesting books suggestions everywhere - on the HN (special topics for books but quite often in the random commments), articles, blogs etc. I don't blindly add new books, I first research it for a few minutes (table of content, reviews, similar books).

I also recommend Farnam Street Blog (http://www.farnamstreetblog.com/) for a lot of interesting suggestions.