The low energy description of a stack of D-branes probing a Calabi-Yau singularity is in general a quiver gauge theory. The construction provides a large class of examples generalizing the original AdS/CFT correspondence, and as such leads to a deeper understanding both of strongly coupled gauge theories and string theory in curved backgrounds. I will attempt to explain the role of exceptional collections in deriving these gauge theories, focusing on an interesting new set of examples, the $L^{a,b,c}$ spaces presented in hep-th/0504225 by Cvetic, Lu, Page and Pope.