  We give a natural family of Bridgeland stability conditions on the derived
category of a smooth projective complex surface S and describe ``wall-crossing
behavior'' for objects with the same invariants as $\cO_C(H)$ when H generates
Pic(S) and $C \in |H|$. If, in addition, S is a K3 or Abelian surface, we use
this description to construct a sequence of fine moduli spaces of
Bridgeland-stable objects via Mukai flops and generalized elementary
modifications of the universal coherent sheaf. We also discover a natural
generalization of Thaddeus' stable pairs for curves embedded in the moduli
spaces.
