Extremely handy site with calculators and converters (weight to molarity, centrifuge rotor speed, buffer concentration, unit conversions, etc.) Look under "PROTOCOLS" for buffers and "PROGRAMS" for calculators.
Provides protein scientists, biochemists, molecular biologists, geneticists, and others with the first comprehensive suite of protocols for protein science.
VADLO is a free online search tool for protocols, online tools, powerpoint presentations and software contributed by a number of institutions and molecular biology blog sources.