The National Consumers League, Internet Fraud Watch published two surveys on Web e-mail scams: Top 10 Internet Scams 2001 (includes data on Type of Complaint, Percentage of Total Complaints and Average Loss), and Ages of Consumers Who Filed Complaints, 2001 (includes Percentage of Total Complaints). The surveys are available in tabular format on this webpage.
The longest continuously running global e-mail scam, in operation since the 1980s, is the Nigerian e-mail fraud. Doubtless you have received such e-mails on a daily basis if you are not using blocking software. For more information, see this United States Secret Service site on what is known as Advance Fee Fraud (AFF) or “4-1-9” fraud, which refers to the section of the Nigerian Penal Code on fraud schemes.
See also this article from CNN today, Latest ID theft scam: Fake job listings. Monster.com e-mailed its users and stated “regrettably, from time to time, false job postings are listed online and used to illegally collect personal information from unsuspecting job seekers.”