A good amount comes from my in-laws as they are retired and semi-retired and have more time to read. Plus my mother-in-law is a speed reader and can finish a 400+ page book in 2 afternoons.

Although I never thought to try these before, I've found several good books from book bloggers. I've been visiting a fair number of different bloggers in the course of trying to market the book my wife and I recently published and I almost always end up scrolling through their blog and clicking on some of the ads and previously reviewed books. One even opened me up to a genre I didn't even know about: Steampunk/fantasy It was interesting, to say the least.

I'm too lazy to scroll up and see who was the first to say it, but I agree that Amazon is a good place to find new books. The fact that they usually have the first few pages as a preview helps as well. You can 'test the water' as it were to see if you like the style of writing of that particular author.