Here is a great article on how skimmers work and how to identity them.
How to Avoid Credit Card Skimmers
Particularly interesting (at least for me) is a link in the article...that show photos of the types of skimmers being used these days.
All About Skimmers — Krebs on Security
I always thought I could identify a skimmer, but after looking at the photos (in the second link above)...I'm now going to be really paranoid.
