I've added some Bible study sites to the bar on the right. Here's a bit more information about each of them.
E-Sword is the finest free Bible study software that I know of. It's geared toward the serious student. Besides lots of English translations (many free), you'll find other modern languages, Greek and Hebrew, Bible commentaries, Bible dictionaries, maps, devotionals and more--much of which is free. Download it! Then make a donation.
ESV Online is one of my two favorite translations. The web site is well-designed, with a built-in editor that you can use for creating notes for a sermon or lesson about a passage. It saves your place and saves your notes; lets you highlight text in any of several colors.
HCSB Study Bible is my other favorite translation. It includes all of the study Bible's notes. One excellent feature: If you hover over a word, the original Greek or Hebrew word pops up, along with a definition.
NET Bible comes with more translation notes than you'll ever want.
Search God's Word has various translations and commentaries and more. It's a bit cluttered, but useful.