This website offers a large number of sentences, just search for any character or word and you can view hundreds of examples of how it's used in Chinese. This is mostly useful once you have the basics down, because these examples aren't adapted for non-native speakers, so beginners will have a hard time understanding them.

I use this site both when I write (to check how a word is used) and when I read (to see if I certain usage is common). It's also a quick way of finding example sentences for flashcards. Sentences are presented in both Chinese and English, but I'd be a bit careful using this as translation help. The sentences is both languages are fine, but the translations are sometimes not ideal.