  This is a survey on the combinatorics and geometry of integrable
representations of quantum affine Lie algebras with a particular focus on level
0. Pictures and examples are included to illustrate the affine Weyl group
orbits, crystal graphs and Macdonald polynomials that provide detailed
understanding of the structure of the extremal weight modules and their
characters. The final section surveys the alcove walk method of working with
the positive level, negative level and level zero affine flag varieties and
describes the corresponding actions of the affine Hecke algebra.
