Teresa Nielson in her 2002 "The underlying forms of fraud" lists seven varieties of Confidence Game:

• Simple misrepresentation.
• Using high-pressure tactics to confuse or intimidate the victim.
• Shell games, sleights of hand, and switch-and-retraction cons: the pigeon drop, the Jamaican switch, Three-Card Monte, etc.
• The Spanish Prisoner
• Ponzi Schemes
• Pyramid schemes
• Selling information about, or access to, uncommon opportunities

Wikipedia's current "List of confidence tricks" article has a more ornate schema:

• Get-rich-quick schemes

Salting * Spanish Prisoner

* Persuasion tricks

Grandparent scam * Romance scam * Fortune-telling fraud

* Gold brick scams

Pig in a poke (cat in a bag) * Thai gems * White-van speakers * Iraqi Dinar

* Extortion or false-injury tricks

Badger game * Bogus dry-cleaning bill scam * Clip joint * Coin-matching game * Fraudulent collection agencies * Bogus or fraudulent law firms * Insurance fraud

* Gambling tricks

Fiddle game * Glim-dropper * Lottery fraud by proxy * Three-card Monte

* Spurious qualifications or endorsements

Diploma mill * Vanity publications and awards * Who's Who scam * World Luxury Association

* Online scams

Fake antivirus * Phishing * Fake support call

* Other confidence tricks and scams

Art student * Big Store * Change raising * Fake casting agent scam * Fraudulent directory solicitations * Jam Auction * Money exchange * Mystery shopping * Pigeon drop * Predatory journals * Promotional cheque * Psychic surgery * Rain making * Recovery room * Rental scams * Rip deal * Unsolicited goods * Wedding planner scam * Blessing scam * Pay up or be arrested scam * Dropped Wallet scam

... not as well-organized or structured as it might be, and all (not including simple cheats) essentially variants on the same thing: a wonderful opportunity, secret or otherwise unavailable to others, to make a huge profit on a small investment.

(cf. Techniques of Financial Fraud (2015-05-02), ...) - ^z - 2016-02-03