  Since its conception, Doppler tomography has matured into a versatile and
widely used tool. It exploits the information contained in the
highly-structured spectral line-profiles typically observed in
mass-transferring binaries. Using inversion techniques akin to medical imaging,
it permits the reconstruction of Doppler maps that image the accretion flow on
micro-arcsecond scales. I summarise the basic concepts behind the technique and
highlight two recent results; the use of donor star emission as a means to
system parameter determination, and the real-time movies of the evolving
accretion flow in the cataclysmic variable WZ Sge during its 2001 outburst. I
conclude with future opportunities in Doppler tomography by exploiting the
combination of superior data sets, second generation reconstruction codes and
simulated theoretical tomograms to delve deeper into the physics of accretion
flows.
