If you're into ebooks and want to read the most powerful sermons written since the reformation, I highly reccommend going to ebay and looking up "THE WORKS OF...." then type in Martin Luther, George Whitefield, Johnathan Edawrds, Moravians, John Wesley, Andrew Murray, George Muller, Charles Finney, Charles Spurgeon & D.L. Moody.
There were the men who completely changed the face of religion forver during the Protestant Reformation and into the 1st & 2nd Great Awakenings. The names I listed are all from different "denominations" who understood the only christian principal that has and will change the world and that is living a life in full submition to the Holy Spirit, not some man made doctrine based on flawed human reasoning. Personally I reccommend Luther, Whirefield, Murray, Muller & Finney.
What you willl find are the scanned copies of their life's work in .PDF format. These are easy to find and are ussually pretty cheap ($5 to $10 each) seeing as they were written and published long before there was ever such a thing as copyright laws. You can also find cd's comtaining the works of the early church fathers, from the period after the disciples and before the catholic church, which are a great read also