supergravity solutions describing the Hanany-Witten effect in which all branes involved are treated as gravitating objects that affect the bulk spacetime fields (and thus the other branes). This construction then leads to a puzzle [@Tdual] involving a certain ‘flux-expulsion’ property of the D6-brane.

We then turn in a rather different direction to discuss how D6-branes may be used to derive and understand a certain ‘confinement mod 2’ effect of D0-branes in the (symmetric) background created by a unit charged D8-brane [@half]. Finally, we make a further radical change in direction to discuss the issue of the consistency of negative tension string-theoretic constructions with black hole thermodynamics and how the study of orientifold 6-planes promises to provide a resolution.

Despite the wide variety of physical questions that will be discussed, all of these issues will be studied using the same basic fact that six-branes have an easily controlled strong coupling description. While the absence of a gravity/gauge-theory duality [@ISMY] for D6-branes may sometimes make these branes seem less exciting than their lower dimensional cousins, I hope that the reader is impressed with the variety of issues that can be raised, addressed, and resolved in the context of six-branes.

The smooth picture 