We review here the advances that have been made in methodology using the analytical ultracentrifuge for characterising polydisperse polymer systems with a quasi-continuous distribution of molecular weight. These advances include improved ways of defining the weight and z-average molecular weights of a distribution from sedimentation equilibrium experiments and hence the ratio Mz/Mw, off-line calibration of size exclusion chromatography by sedimentation equilibrium and conversion of a sedimentation coefficient distribution into a molecular weight distribution. Although these methods are applicable to other polymeric systems, we focus on polysaccharides, mucins and other glycoconjugates, systems which particularly benefit from the availability of recently available long optical path length cells for the minimisation of complications through thermodynamic non-ideality.