The Evangelical Bible guys posted up a Google Trends link on Bible versions. I did some tweaking to the version's acronym (which I think the average person is more familiar with) and some of the results surprised me.
http://www.google.com/trends/explore#q=NIV%2C%20KJV%2C%20NKJV%2C%20ESV%2C%20NLT&geo=US&cmpt=q
Surprises
http://www.google.com/trends/explore#q=NIV%2C%20KJV%2C%20NKJV%2C%20ESV%2C%20NLT&geo=US&cmpt=q
Surprises
- The KJV surge in recent times. (I would have said the KJV would somewhat slowly decrease. Perhaps more people are still getting online or yearning for the beauty of the KJV language.)
- The NIV's steady drop. (If you look back, the NIV has gone from total domination of the Bible market to being much closer to the ESV. Not hugely surprising, but it's a large drop nonetheless.)
- The ESV's rise. (Again, not huge, yet it has gained.)
- The relative unpopularity of the NLT. (It was on the rise, but plateaued.)
- When I swapped out the HCSB and NRSV, they were the lowest.