I am looking for a more efficient way to find example sentences and I was wondering if anyone knows of a search engine with more powerful search functions than that offered by JReK.

Basically, I'd like the option to search for words within a specified number of words of another word. If anyone has ever used Factiva for work or study then you'll know this is a very useful feature when trying to retrieve particular information.

This feature would be particularly useful when you're looking for example sentences with two or more words with a common theme that you would like to see used together. For example:

食堂 within n words of 食べる

津波 within n words of 避難

金融 within n words of 債務 within n words of 不履行

食中毒 within n words of 吐き気 within n words of 下痢

It would be a pretty efficient way to get more out of each example sentence. Does anyone know of any search engine where this is possible?

Yes.
http://www.kotonoha.gr.jp/shonagon/

Edit: The official term for something like this is corpus by the way. 日本語 コーパス is what I put into Google to find that if you want to see what else is out there.

This is really great. It's exactly what I was looking for. Thanks a lot!