One good resource (that sadly has lots of ads) is bible.crosswalk.com. This link will take you directly to their Bible study section. If you click on a word in the text it will show you the Strong's number, the lexicon definition, a verse count of where the word appears (like a concordance would). The nice thing about Crosswalk is that it has all the latest translations and is one click to all the info.
You can use Crosswalk or use the following tools to complete a word study. These next tools are from the Blue Letter Bible, which is a great online Bible study resource.
To use the Blue Letter Bible tools, first you need to find the Strong's number for the word you are interested in. You can use either the verse lookup (if you know what passage has the keyword you are interested in), or you can use their concordance search tool to find the word and verse. Once you get the Strong's number write it down, then proceed to the next step.
|Phrase Search / Concordance
Once you have the Strong's number for the keyword you are interested, you can enter it here to get a lexicon definition and concordance listing of where the word is used. Note for NT words select Greek, for OT words select Hebrew.
e.g. 2424 Greek
More Bible Study Tools
Here are some other resouces that can help you study the scriptures
Some serious notes on studying the scriptures properly. Hermeneutics Packet
www.e-sword.net Complete Bible Study tool. Tons of add-ins are provided.
Other Online Resources
Christian Classics Ethereal Library
Online sources of scripture.
Xenos CF Bible Tools
e bible A new Bible tool
Crosswalk Bible Study
Blue Letter Bible
The Unbound Bible