  We show that in a two-component Bose gas with Rashba spin-orbit coupling
(SOC) two atoms can form bound states (Rashbons) with any intra-species
scattering length. At zero center-of-mass momentum there are two degenerate
Rashbons due to time-reversal symmetry, but the degeneracy is lifted at finite
in-plane momentum with two different effective masses. A stable Rashbon
condensation can be created in a dilute system with weakly attractive
intra-species and repulsive inter-species interactions. The critical
temperature of Rashbon condensation is about six times smaller than the BEC
transition temperature of an ideal Bose gas. Due Rashba SOC, excitations in the
Rashbon condensation phase are anisotropic in momentum space.
