Google has also released a full-web 5-gram corpus that contains "counts for all 1,176,470,663 five-word sequences that appear at least 40 times" Its fun to try training on that.
As the comments (on the google page) illustrate, this corpus is close to useless unless you're a university researcher. Commercial use of this data costs big $$$. And if you're an independent you still have to pay $150 or so to get LDC to mail the six DVDs to you.
One of the painful things about commercial NLP work is lack of good datasets without restrictions. There are some treasures like WordNet (which is a lexical db). For tagged data I found the American National Corpus but the excerpt they release without restrictions is too little data and it contains only a few styles of writing.
I had to spend a lot of time gathering, fleecing, and marking up my own data to make After the Deadline.
That is what I ended up doing. Except this is raw data. Usually NLP researchers work from corpora that are already segmented into sentences and tagged with part-of-speech tags. I had to go through the hassle of segmenting and marking up the Wikipedia and Project Gutenberg.
This is why GOOG silently backed Wikipedia: to gain quality content regarding syntax and semantics. Other than give people a "good reason to surf" and hit "ads" [trackers] down the road.
http://googleresearch.blogspot.com/2006/08/all-our-n-gram-ar...