Baler, re: gambling and Everquest
http://www.nickyee.com/eqt/skinner.html
Interesting little undergrad-esque blurb about addictive traits/mechanisms common to MMORPGs and gambling both. He's a little stuck on the manipulative aspect of design, and does not acknowledge that people can greatly enjoy these mechanisms without overindulging to the point of real life harm, but still neat.
I love Everquest and am not overly concerned by the overlap of gameification and addiction...but maybe that's cause I'm already addicted to gaming in general and would not stop if Everquest were not available ;p