A few important ones: Lempel-Ziv compression: Though it's hard to point to things that would have been impossible without it, it's saved so much transfer and s

A few important ones: Lempel-Ziv compression: Though it's hard to point to things that would have been impossible without it, it's saved so much transfer and storage capacity in its time that the economic impact would be huge. Apriori association mining: Of fairly limited application, but it's use in market basket data has probably had quite a large impact on our retail sector for one.