Advanced NFL Stats just released the play by play of the 2002 season on.
I some quick analysis of the data using Hive and MapReduce and decided to look at incomplete passes. The code is here on my GitHub account.
Most incomplete passes from a QB to a receiver.
Most incomplete passes from a QB to a receiver averaged out over the number of seasons they played together and ordered by the highest average.
Update: Added in 2010 data.