I'm thrilled to see this launched.  This is my 20% project.  I implemented the "Ngram compositions" which allows you to do math on the ngrams.  

It let's you see cool things like the compoundification of "applesauce" over the 20th century:

http://books.google.com/ngrams/graph?content=applesauce%2F%28applesauce%2Bapple+sauce%29&year_start=1900&year_end=2000&corpus=15&smoothing=3&share=

I'll post a few more of my favorite examples individually.