Research opportunities and techniques are reviewed for the application of hard 
x-ray pulsed free-electron lasers (XFEL) to structural biology. These include 
the imaging of protein nanocrystals, single particles such as viruses, 
pump--probe experiments for time-resolved nanocrystallography, and snapshot 
wide-angle x-ray scattering (WAXS) from molecules in solution. The use of 
femtosecond exposure times, rather than freezing of samples, as a means of 
minimizing radiation damage is shown to open up new opportunities for the 
molecular imaging of biochemical reactions at room temperature in solution. This 
is possible using a 'diffract-and-destroy' mode in which the incident pulse 
terminates before radiation damage begins. Methods for delivering hundreds of 
hydrated bioparticles per second (in random orientations) to a pulsed x-ray beam 
are described. New data analysis approaches are outlined for the correlated 
fluctuations in fast WAXS, for protein nanocrystals just a few molecules on a 
side, and for the continuous x-ray scattering from a single virus. Methods for 
determining the orientation of a molecule from its diffraction pattern are 
reviewed. Methods for the preparation of protein nanocrystals are also reviewed. 
New opportunities for solving the phase problem for XFEL data are outlined. A 
summary of the latest results is given, which now extend to atomic resolution 
for nanocrystals. Possibilities for time-resolved chemistry using fast WAXS 
(solution scattering) from mixtures is reviewed, toward the general goal of 
making molecular movies of biochemical processes.