Thermal motions in macromolecules have been shown to be highly relevant in biology, allowing, for example, functionally important conformational changes to occur on much longer time-scales. Because of the values of their associated wavelengths and energies, thermal and cold neutrons are uniquely suitable for the characterization of these confined pico- to nano-second motions. Information useful to furthering understanding in biology, however, is mostly derived from measurements on many different systems under various conditions. Incoherent elastic neutron scattering temperature scans allow rapid screening of samples and conditions. The power of the method is demonstrated by recent results on proteins in solution and complex biological systems.