IQ Tests

General:

• high quality MENSA IQ test
• hard - IQ more than 130
• world's quickest free IQ test
• free IQ test
• IQ Test

Extremely difficult:

• Paul Cooijman
• uncommonly difficult IQ tests - links
• The Hoeflin Power Test
• The Ultra Test
• The Titan Test
• The Smartest Person in the World Contest
• Laurent Dubois