Absract: “EXX” phenomena in macroscopic, microscopic and nanoscopic metal-semiconductor hybrid structures will be described. Here E = extraordinary and XX = magnetoresistance (EMR), [1,2] piezoconductance (EPC),  optoconductance (EOC),  and electroconductance (EEC).  The underlying phyiscs of EXX phenomena will be elucidated with particular emphasis on both analytic and finite element analysis methods to quantitatively account for the observed EXX enhancement. Surprising new aspects of the mesoscopic physics of the nano-hybrid structures will be addressed including the recently discovered inverse-EOC or I-EOC. So to will new 3-dimensional EMR phenomena. Time permitting, it will also be shown how EXX nanosensors can be employed for several applications ranging from ultra high density magnetic recording to the study of the properties of cancer cells with ultra-high spatial resolution.