Last week's column about loading e-coupons to loyalty cards led to reader comments on store loyalty cards! Love them or loathe them, my readers are chiming in. Several were concerned about privacy.

As many of you already know, I am a big fan of Kangaroo Express gas stations because of the amazing deals I have been able to get. Last year, I wrote about its unusual marketing project called the Roo Cup Club. Members receive text messages with...