https://en.wikipedia.org/wiki/RetrievalWare is especially known for its use by government intelligence agencies.[1]
[1] http://40.media.tumblr.com/c92f59692956551c96d13f26a9703a7e/tumblr_nsoe1rdQls1sofvubo2_1280.jpg
[2] http://41.media.tumblr.com/6dc32deabf95a6f63ace5585ce4b7558/tumblr_nsoe1rdQls1sofvubo1_1280.jpg