I'm not going to erase any predictions; if I change my mind I'll add an updated prediction.

An excellent site for major predictions (often with significant wagers) is Long Bets.

Economy

• July, 2002: The NASDAQ index will drop below 900 and the DOW below 6000 before the end of 2003. [WRONG: it climbed back to about 2000 at the end of 2003.]
• July, 2002: At least 5 more Fortune-100 companies (after Enron and Worldcom) will declare bankruptcy before 2005; accounting tricks will have hidden their large losses until their collapse.
• July, 2002: By 2100, most developing countries except those in sub-Saharan Africa will enjoy a standard of living comparable to today's in the western world. The exceptions will be due to political repression, not fundamental limits.
• July, 2002: The US will remain the world's largest economy through 2100.
• July, 2002: Russia will not become a technological leader by 2020. It will have a per-capita GDP lower than China's in 2050. [Opposing views: Esther Dyson]

Technology

at
• June, 2004: Spam email will never be greatly reduced by any technological fix. See my essay for more detail.
• July, 2002: Moore's law will run out of steam by 2012. Moore's law suggests that computers in 2022 will have 10000x the power of todays (say, 30 TIPS) but I think they will have no more than 100x (say, 300 GIPS). [Opposing views: Sheldon Renan]
• July, 2002: Robot butlers, capable of cooking, cleaning, and interacting in fairly natural ways will become available by 2010 and common by 2020.
• July, 2002: CDs and DVDs compatible with today's will remain the most common way to buy or rent music or video through 2020.
• July, 2002: Word processors, spreadsheets, web browsers, and email will have substantially the same features in 2020 as today.
• July, 2002: In 2030, most people will communicate over telephones much like today's, and telephones will still be dialed like they are today. Videoconferencing will remain an exotic feature.
• July, 2002: In 2075, most fiction will be read in paper book form.
• July, 2002: In 2050, most people will still drive to work in a car with a gasoline engine getting less than 60 MPG. The real price of gasoline in the US will not rise by more than a factor of 3.
• July, 2002: Computers available to consumers will have hardware controls to prevent copying of CDs and DVDs by 2020. Only a few hobbyists will be able to copy digital media.
• July, 2002: Most consumers will watch NTSC analog television through 2020; digital or HDTV television will remain a curiosity for audiophiles.
• July, 2002: Video on demand will not supplant video store rentals before 2020.
• July, 2002: Voice recognition will not supplant keyboards for tasks such as word processing before 2050.
• July, 2002: Less than 5% of US homes will have internet connections of more than 500 kbits by 2010.
• July, 2002: Supersonic air travel will account for only a tiny fraction of all air travel in 2100. Airport delays will continue to add more than an hour to most trips.
• July, 2002: No person will set foot on the moon or another planet between now and 2100. [Opposing views: Hemant Sharma]

World

• July, 2002: There will not be a nuclear weapon detonated in anger before 2100.
• July, 2002: Taiwan will still be an effectively independent country in 2050; China will still deny their independence.
• July, 2002: There will not be an effective world government before 2100. [Opposing view: Colin R. Glassey]
• July, 2002: The population of the world will not exceed 10 billion before 2100.

Medicine

• July, 2002: AIDS will cause 100 million deaths before being eradicated.
• July, 2002: Before 2050 a new disease, not due to biotechnology but simply a naturally evolved virus, will cause at least 100 million deaths.
• July, 2002: Prion-borne diseases (as Creutzfeldt-Jakob disease) will not cause more than 3000 human deaths before 2100.
• July, 2002: No disease epidemic will ever again wipe out more than 1/4 of mankind.
• July, 2002: By 2100, most Americans will live to be over 120 years old. [Opposing view: S. Jay Olshansky]
• Aug, 2002: By 2030, most forms of cancer will be found to be viral in origin.