It is well recognized that novel computational models, devices and technologies are needed in order to sustain the remarkable advancement of CMOS-based VLSI circuits and systems. Regardless of the models, devices and technologies, any enhancement/replacement to CMOS must show significant gains in at least one of the key metrics (including speed, power and cost) for at least a subset of application domains currently employing CMOS circuits. In addition, effective defect tolerant techniques are a critical factor for the successful adoption of any new computing device due to the fact that nano-scale structures will have defect rates much higher than today's CMOS chips. The task of identifying application domains that could benefit the most from a new model/device/technology and ensuring that the resultant system meets functional requirements in the presence of defects requires synergistic efforts of physical scientists, and circuit and system design researchers. This paper contains a collection of three contributions-each focusing on one particular emergent technology-presenting a basic introduction on the technologies, some of their unique features in contrast with CMOS, potential application domains for these technologies, and new opportunities that they may bring forward in defect tolerance design. The contributions include both traditional and non-traditional state representations which use either electronic or magnetic interactions.