Nonlinear regression is one of the most common analyses used by biological scientists, yet it is a topic ignored by most statistics text books. These resources will help you learn, and master, nonlinear curve fitting.
Learning nonlinear regression - While the math of nonlinear regression is complicated, learning to use nonlinear regression programs sensibly is no harder than any other statistical technique.
Global nonlinear regression - Global curve fitting fits curves to a family of data sets at once, sharing the best-fit value of selected parameters to find one best-fit value that applies to the entire family, rather than individual best-fit values for each data set. Global curve fitting is an important new feature of Prism 4, and is more versatile than you might guess.