Barry Beyerstein is professor of neuropsychology at Simon Fraser University in Canada. He is a leading skeptic, on the Executive Council of the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP), and a frequent contributor to The Skeptical Inquirer.
They have an electronic newsletter, 'The Rational Enquirer'. Here's an article, excerpted of their first letter, along with Barry's own cult checklist (by courtesy of B. Beyerstein).

BC Skeptics website: http://eslvcr.firplug.net/bcskeptics.
Website for the international skeptics organization, CSICOP: www.csicop.org

Who is vulnerable to cult recruitment?

- We all are at some time in our lives. Most of us satisfy the foregoing needs within our normal range of relationships and this gives us a certain amount of protection, as long as we stay within that framework.

- Cult recruits are not any more likely to be mentally ill, less intelligent, or less well educated than the average population.

Nor are they necessarily more gullible on average. They do tend, however, to be “seekers,” constantly looking for pat answers and magical solutions for personal or societal problems. They are often driven to find answers (any answer) to the great metaphysical questions, rather than live with uncertainty. Those who have a higher tolerance for ambiguity can live with the acceptance that such things are ultimately unknowable.

- How can we recognize a cult? A fair use of the cult label for a questionable organization would require the presence of most of the items on the following checklist.

Does the group:

(a) engage in deceptive recruitment practices? (recruiters typically disguise the true nature and aims of the group when seeking converts)

(b) tend to target vulnerable individuals, as outlined above?

(c) offer unconditional affirmation and support initially, but soon make its continuance contingent on obedience?

(d) have a closed social system that makes a special effort to isolate acolytes from family, friends, etc.?

(e) use constant bombardment with pro-group and pro-leader messages and exclusion of other messages?

(f) have a rigid, authoritarian hierarchy?

(g) have a leader and ruling clique that are perceived to possess infallible insight, supernatural powers, etc.? Do they claim to have been chosen by some higher authority to rule, and thus to be excused from the normal social restrictions on one’s behavior?

(h) have an eclectic, often muddled and internally contradictory, set of teachings - usually a magic-laden philosophy that claims to have infallible answers to those “big ticket” questions of existence?

(i) have a strict behavior code that governs all aspects of how one should think, feel, and act? Are there strong penalties for deviation?

(j) instill fear of outsiders (the “bunker mentality”)? Does the group try to convince members they are powerless to act without the group’s support and that the world “out there” is uncaring and hostile?

(k) engage in major forms of exploitation (e.g., financial, occupational, or sexual - of self, spouse, or children)?

(l) demand immoral, unethical, or illegal activity on the part of its members?

Some cult leaders are unequivocally psychopaths and con-artists, but others spring from more complex roots. The late British psychiatrist Anthony Storr published a book (Feet of Clay) that discusses common attributes in those who become cult leaders. There often appears in their backgrounds some kind of serious psychological crisis that they have surmounted by interpreting it as a special calling to some higher purpose. Even those gurus who start out believing they are on an inspired mission to improve the lives of others usually succumb to the seductions of unbridled adoration and privilege, resulting ultimately in disaster. It is as Lord Acton so wisely admonished:

“Power corrupts and absolute power corrupts absolutely.”

"Barry was contacted a couple of months before this seminar by an emissary from the French Prime Minister’s office, M. Jean-Yves Defay, who was on a North American fact-finding tour. The French government, like that of Germany, has become concerned about the growing influence of cults at high levels in the business community, the media, and the government bureaucracy. The French administration was seeking to compare notes on similar matters in other jurisdictions. The Prime Minister’s special representative was surprised to learn that the Canadian government, and even the Americans, have not been taking much note of cult influences on this side of the Atlantic. M. Defay was particularly concerned about irregularities in the ways in which the US Internal Revenue Service abruptly abandoned its decades-long opposition to tax exempt status for the Church of Scientology. The head of the IRS, after a brief, unheralded meeting with a senior Scientologist, suddenly ordered his officials (over their strong protest) to cease trying to collect millions in back taxes from Scientology and to grant the “church” tax exempt status thenceforth. In Europe, the issue of cult influences in society is gaining in importance while here it seems to have attracted little concern."