“One Stop” Bible Study Tools: Each includes interlinear Bibles, commentaries, word study resources, concordances, Bible dictionaries, sermon illustrations, and other online resources.
http://www.biblegateway.com
http://www.biblestudytools.net
http://www.bibliapedia.com
http://www.blueletterbible.org

Bibles
Free audio downloads of the Bible: http://www.audiotreasure.com/
Inexpensive computer concordance: http://www.discountchristian.com/freesoftware.html

Bible Dictionaries
Baker’s Evangelical Dictionary of Biblical Theology, Hitchcock’s Bible Name Dictionary, Smith’s Bible Dictionary, and more: http://www.biblestudytools.net/Dictionaries/
The Holman Bible Dictionary: http://www.studylight.org/dic/hbd/

Bible Encyclopedias
International Standard Bible Encyclopedia: http://www.studylight.org/enc/isb/
A Web Bible Encyclopedia boasting over 4,100 articles, frequently updated: http://www.christiananswers.net/dictionary/home.html

Commentaries
J.W. McGarvey’s Harmony of the Four Gospels, the Geneva Study Bible, and even A.T. Robertson’s Word Studies on the Greek New Testament: http://www.biblestudytools.net/Commentaries/
Includes: John Calvin, Alfred Edersheim, Matthew Henry, J.B. Lightfoot, Martin Luther, and Charles Spurgeon: http://cf.blueletterbible.org/commentaries/
Searchable database by topic or text: http://www.mybibletools.com/bible/commentaries.htm.

Concordances/Word Studies
http://www.studylight.org/isb/. Search for Bible words in English, Greek, and Hebrew.
http://www.blueletterbible.com. Search for Bible words in English, Greek, and Hebrew.
In doing biblical word studies, you will not need much more than this website has to offer: http://www.mybibletools.com/bible/word-study.htm
Search tools for: Strong’s concordance, Brown-Driver-Briggs Hebrew Lexicon, Thayer’s Greek Lexicon, Encarta Encyclopedia: www.eliyah.com/lexicon.html