Many of the fascinating applications of nanophotonics utilize the photothermal effects in which nanophotonic resonances enhance optical absorption and generate heat. The resulting high temperature in nanostructures has been applied in water purification, medical treatment and chemical reactions. However, theoretical modeling of nanophotonic thermal effects is often challenging because of the involved multi-physical processes. Here, we demonstrate three novel applications of nanophotonic photothermal effects with a particular emphasis on theoretical modeling: plasmon-accelerated photothermal curing of epoxy, optical-force-dominated directional reshaping of photothermally softened nanoparticles, and photothermoelectric effect in a semiconductor device. Our models successfully explained the experimental findings and gave us deeper understanding of the nanoscale photothermal systems.