Blue Letter Bible - www.blueletterbible.org
A great resource for digging deeper into God's word. It has a built in concordance, lexicon, and much, much more.
E-SWORD - www.e-sword.net
If you can not always be online, this is a great piece of software that can help you to find Strongs' numbers, commentaries, parallel bible, and more. Check it out.
P-R-E-C-E-P-T A-U-S-T-I-N - www.preceptaustin.org
A wealth of biblical information that can help in any study you are doing.
BibleStudyTools.com(Library) - www.biblestudytools.com/library/
This is a pretty decent refrence library. Dictionaries, Enclclopedias, Lexicons, Concordances.
Biblos.com - www.biblos.com
A hub for original language tools (the interlinear is helpful for tense) and about any kind of bible study tools, if you can navigate your way through it.