Amazon.com is offering the Kindle version of Heart of Darkness (http://www.amazon.com/Heart-Darkness-Joseph-Conrad-ebook/dp/B0084AMNWQ/ref=sr_1_1?s=books&ie=UTF8&qid=1385496005&sr=1-1&keywords=Heart+of+Darkness) by Joseph Conrad free of charge.
I don't know how long this free offer will last.