http://corpora.informatik.uni-leipzig.de/?dict=en
For each word, the most significant words appearing
- as immediate left neighbor
- as immediate right neighbor
- anywhere within the same sentence
There is also a free download version (mSQL) http://corpora.informatik.uni-leipzig.de/download.html
Do some lookups at The Collins Wordbanks Online English corpus. It is composed of 56 million words of contemporary written and spoken text. Check up some word, idiom or phrasal verb in rhetorical contexts. Notice the settings !. Take your time.
http://www.collins.co.uk/corpus/
BNC British National Corpus (100 million words)
http://www.natcorp.ox.ac.uk/
+
BNC Information about multiple word queries:
http://www.natcorp.ox.ac.uk/using/index.xml.ID=simple
Webster (1913)
http://www.ibiblio.org/webster/#search_form
Notice the query syntax
Michigan Corpus of Academic Spoken English
http://quod.lib.umich.edu/m/micase/
Site is sometimes temporarily shut down
http://www.tooyoo.l.u-tokyo.ac.jp/~kmatsum/corpus/myconc.html