From time to time, someone asks me what Bible study tools I use. Aside from commentaries and reference books, I often use the ESVBible.org as my starting point.
In addition to the free features (search, audio, personal note-taking, etc.), the ESV Bible online offers several options that can be purchased for a small amount. I use the ESV Study Bible notes and the Greek Interlinear Bible. But one can also add MacArthur’s notes, the Literary Study Bible notes and others.
The nice part about studying the Bible online is you can take your study everywhere you go. Also, all the cross references and notes are linked, so you can survey the landscape of any particular topic fairly quickly.
And bonus, Crossway has recently overhauled the site to make it even more facile for study. So check out ESVBible.org and give it a try!