Competing interactions are a common feature in physical and biological systems. Novel and complex phenomena emerge as systems attempt to resolve the frustration by reorganizing the underlying degrees of freedom. An extreme situation can be found in magnetic systems with triangular spin arrangements where all magnetic interactions cannot be satisfied due to the topology of the lattice, possibly leading to an infinite zero-point entropy. The important issues in this field are (1) what the nature of the spin liquid phase is and (2) how the system responds to the ground state degeneracy. I will discuss these issues with neutron scattering results obtained from some spinel antiferromagnets AM2O4 where the transition metal M ions form a network of corner-sharing tetrahedrons.