Trapped cold atoms systems have emerged as a new frontier of research in condensed matter physics. In particular, physics associated with strong interaction/correlation in such systems is of strong current interest. In this talk I will describe several examples in which quantum phase transitions and emergent particles with exotic properties arise in such systems, which do not have counter parts in traditional electronic condensed matter systems. These include: (i) a transition from an integer quantum Hall phase to a fractional quantum Hall phase where the critical theory is that of a massless relativistic semion; (ii) new universality class of superfluid-insulator transition in Bose-Fermi mixtures, and high-Tc p-wave fermion pairing mediated by quantum critical fluctuations; and (iii) the possibility of realizing supersymmetry in Bose-Fermi mixtures, and detecting a Goldstone fermion called Goldstino in such systems.