In this talk, I will report our recent investigation of few-body processes with an ultracold 23Na and 87Rb system. We observed a dimer-dimer resonance between weakly bound NaRb Feshbach molecules when the interspecies atomic interaction is tuned near a Feshbach resonance. We also found an atom-dimer resonance closely related to the Efimov trimer in a mixture of Rb and NaRb Feshbach molecules. Our results agree qualitatively with a model based on a two-body Gaussian interaction, but reaching a quantitative agreement is still challenging. I will also report briefly on our recent achievement of ultracold NaRb polar molecules in the absolute ground state.