Earlier today Google announced a number of new search options for the Ngram Viewer. You can now search for a word and only return results where it is specifically used as a noun and not a verb (or vice versa). You can find words when they are used at the beginning or the end of a sentence.
You can even search for words where one is used as an adjective or adverb of the other. And I think my favorite new search option is the ability to combine several phrases into a single graph:
That last one is gong to prove very useful for coping with spelling differences (e-book/ebook, color/colour, etc) as well as showing, like you see in the graph above, how one word or phrase supplants the other.
There are so many new search options that I have only touched on the highlights. You can find a complete list of the search terms here.