What are some data mining case studies that use simple data mining algorithms?

A. Bitukov answers: Xiaohua Hu wrote excellent case study. It was published in Journal of Applied Intelligence, A Data Mining Approach for Retailing Bank Customer Attrition Analysis.

Also, here are a couple good case studies from the Journal of Database Marketing:

Time to fly: An approach to segmentation and modelling customer dynamics in the travel sector, by Nigel Magson and David Dipple

Predictive modelling applied to the retention of mortgages, by Leonard Paas

Gregory Piatetsky-Shapiro adds: also see proceedings of several workshops on Data Mining Case Studies