Until recently, the investigation of cold (< 1 K) neutral reactions has been limited due to the difficulties of experimentally achieving collision energies in this regime. Several methods have emerged in the last decade to overcome this challenge, such as Stark and Zeeman deceleration, buffer gas cooling, laser-cooled ion-trapping, and merging molecular beams. The latter involves reducing the relative velocity of two supersonic expansions to tune well below 1 K of collisional energy. At such low energies, reaction dynamics are dominated by non-classical effects which manifest due to de Broglie wavelengths that are equal to or larger than the interaction length of the colliding partners. Such effects, termed resonances, are typically tunneling events through entrance channel barriers in the translational and/or centrifugal interaction potentials. Recent work involving isotopic, excited state, and anisotropic effects will be discussed.