http://blog.backblaze.com/2014/01/21/what-hard-drive-should-i-buy/
These posts were an outgrowth of the careful work that we’ve done at Backblaze to find the most cost-effective disk drives. Running a truly unlimited online backup service for only $5 per month means our cloud storage needs to be very efficient and we need to quickly figure out which drives work.
You may have already seen this -- it's popped up at a couple few sites already -- but for anyone that hasn't seen it there's some good info on which drives last & which ones have high failure rates.