Since I'm currently reading Jesus, Interrupted, I thought this would be a good time to cover some of the resources I use for studying the Bible.
First there are the more general sites. Bible Gateway is pretty much the default site for looking up Bible passages in various translations, although the Bible Verse Finder tool offers even more options. Typing a single verse into Bible.cc lets one quickly view it in fifteen translations at once. I also like Blue Letter Bible quite a bit. It has a concordance built in if one searches either the KJV or NASB translation of the Bible. I use this whenever I want to know the precise meaning of a Greek or Hebrew word.
The author of JI, Bart Ehrman, suggests reading the Bible horizontally, comparing multiple passages to look for differences and discrepancies. There are a few tools online that can help aid in this with regard to the gospels. The Five Gospel Parallels page, created by a University of Toronto professor, is the best one I've found. With just a few clicks, one can line up all four gospels (plus other books) to focus on exactly how a particular story is told. Gospelparallels.com is less useful for in-depth study, but works well as a quick way to compare which stories are present in which gospels.
The internet is truly a great thing, isn't it? Just a few decades ago people had to flip through massive books if they wanted to study the Bible, but now we can do in-depth research quickly and easily. If resources like these were around when the early church was deciding on the biblical canon, I bet the Bible would look very different than it does today.