Greek New Testament (with syntax trees)
If you are tired of the same old practice data sets, I may have a treat for you!
The Asia Bible Society has produced syntax tress for the New Testament, using the SBL Greek New Testament text.
To give you an idea of the granularity of the data, the first sentence in Matthew is spread over forty-nine (49) lines of markup.
Not big data in the usual sense but important data.