Last month I wrote about VocabUsage.info, a search engine which gives you example sentences for English words. I have since discovered a few other useful sites in this category. The British National Corpus has nice examples from a wide range of sources (both written and spoken). Unfortunately, the free search is a bit slow and only includes British sources. The Corpus of Contemporary American English is a free, large corpus of American sentences, if you don’t mind the complex interface.