Some people push physical boundaries through body modification or inane stunts and get accolades. Others break through scientific frontiers and get awarded with the Nobel prize. Overclockers, however, do it simply because it's nerdy cool.
Using the AMD Dragon platform and a 3.2GHz Phenom II X4 955 processor, overclockers at QuakeCon (an enthusiast PC convention) managed to bring the CPU clockspeed to just over 7GHz. Instead of liquid Nitrogen that cools to -196 degrees Celsius, this feat was achieved by using liquid Helium which brought the system temperature down to -267 degrees Celsius.
Feel like doing some extreme overclocking on your own PC? Well, don't. For one, you need to be properly trained to handle liquid Helium, on top of years of overclocking experience. Moreover, not all chips are made equal, hence different chips from the same model have varying degrees of tolerance to overclocking. Make a mistake, and you have an expensive mess on your hands. But here's a video made at QuakeCon to make you feel better.