I'm an author who makes a comfortable side income (soon, I hope, my main income if I can leave the day job) and while piracy is what it is, there are two ways you can get free books that no one here has mentioned:
1. Write the author a fan letter! Seriously! I send free books (mobi, epub, pdf -- whatever) when a fan writes me. My ego loves it,a dn readers really love it! Plus, I ask them if they'll join my email list and it's win-win, because I often give away special freebies and this often converts folks into buyers (but fans don't have to buy!).
2. Join a lending group, like the reader boards at Kindleboards.com. Most Kindle and Nook eBooks are lending enabled, which means someone who bought the book can lend it, free, for 2 weeks to another Kindle account owner. Legal, ethical, and you can access more books than you can via pirate sites, typically, because they're available earlier.