First on the shelf is the Blue Letter Bible from Koinonia House. With it you can view the Greek or Hebrew right along side the English (KJV).
Here's another online Bible from Bible Gateway. This one allows you to search the Bible in nine languages and in multiple versions.
The Matthew Henry Commentary. The best I have found online and one of the all time best around. Though historic and sometimes wordy, it is very in-depth and insightful.
Easton's Bible Dictionary. The first study help I bought when I first became a believer was a Bible Dictionary. I still find it indespensible.
The Ray Stedman Library of Sermons and Expository Studies. What others have given us in print about what they have discovered during their own pilgrimmages should be a blessing to us. But they can only be if we read them! Ray Stedman is one of the best in contemporary times.
The Christian Classics Library. This is deep reading from the likes of our early Church Fathers, the Reformers and many contemporaries. Topics cover many subjects concerning our faith. Enough reading for a lifetime. There is also a selection of fiction and Hymns.