One of the classic papers on sentiment analysis utilizes this operator (in 2002, it was AltaVista's NEAR) in the algorithm.<p>"Thumbs Up or Thumbs Down? Semantic Orientation Applied to
Unsupervised Classification of Reviews" by Peter Turney is the paper if anyone is curious.
There was some ancient DOS "e-book" software I had as a young kid that had something like this (e.g. Find "Jacob" within 32 words or 6 verses of "Esau"); finally I know how to do the same thing with the web.
Another thing to add the the Google-Fu toolbox. I wish I had this a bunch of times, since sometimes blogs will appear in search results that mention two topics I'm interested in, but not in the same article.