Free Josh McDowell ebooks
You can download some free ebooks from Josh McDowell at his website They seem to be of older, out of print books. Topics include apologetics, relationships and children's fiction.
Free ebooks of Christian classics
At Puritan Library you can download free ebooks of classic Christian works by authors such as Jonathon Edwards, John Owen, Richard Baxter and many more. Many of the downloads are available in kindle and epub formats.
Heaps of free Mark Driscoll sermons
At the Mars Hill Church website you can download heaps of sermons by Mark Driscoll. I'm currently listening to the 2 Timothy series