  We study the matrix models that describe the BPS bound states of branes
arising from the quiver picture of the derived category. These theories have a
topological partition function that localizes to the Euler character of the
anti-ghost bundle over the classical BPS moduli space. We examine the effective
internal geometry of D6/D2 bound states in the local vertex geometry, using BPS
0-brane probes. The Kahler blowups of the Calabi-Yau that we find utilizing
these quiver theories are a realization of A-model quantum foam in the full IIA
theory.
