  We assess the effects of a collision between two vacuum bubbles in the
thin-wall limit. After describing the outcome of a generic collision possessing
the expected hyperbolic symmetry, we focus on collisions experienced by a
bubble containing positive vacuum energy, which could in principle contain our
observable universe. We provide criteria governing whether the post-collision
domain wall accelerates towards or away from this "observation" bubble, and
discuss the implications for observers located at various positions inside of
the bubble. Then, we identify the class of solutions which have minimal impact
on the interior of the observation bubble, and derive a simple formula for the
energy density of a shell of radiation emitted from such a collision. In the
context of a universe undergoing false vacuum eternal inflation, these
solutions are perhaps the most promising candidates for collisions that could
exist within our past light cone, and therefore in principle be observable.
