Semiconductor memories have have increased fourfold in density about every three years from less than 1K-bit in 1972 to more than 1G-bit in 2002. Applications which historically permitted the technology to trade-off speed and power, now demand both high speed and low power. While the price has dropped from one dollar per 100 bits too less than one dollar per 100 megabits, the production technology has become so complex and expensive that the average multi billion-dollar company can no longer afford it. The circuits have reached geometries so small that semiconductor theories are being altered and fundamental limits are foreseen. While there are undoubtedly many years of life left in the old memory technology, the world is currently taking a hard look at wether there might be a better way. This book explores a range of new memory products and technologies. The concept for some has been around for years, some are completly new and some involve materials that have been in volume production in other type of devices for some time. In addition to looking at using known devices and materials in novel ways, there technologies are being investigated such as DNA memories, light memories, molecular memories, and carbon nanotube memories, as well as the polymer memories which hold the potential for the significant manufacturing reduction.