Scientology attracts people with its offer of a free personality/IQ test. After that the pressure is on to buy Dianetics, the group's philosophy text and to sign up for increasingly expensive 'auditing': i.e., intensive counselling sessions which are supposed to clear warped impressions that prevent optimal functioning of mind and body.
About Scientology – information from Inform
Audio & Video materials
What to get L. Ron Hubbard for his birthday
The Scientology website