I met a snake on the sidewalk. Should I grant it the right-of-way, or should I dispatch it safely to death with my heel?

Common sense would indicate that it depends on the case and the type of snake. If it is a dangerous reptile that could harm others especially children, it should be disposed off. If it does not present any danger at all, it should just be shoveled to the side. (All not on Shabbos). Zohar (Yisro p. 68) tells a story of R’ Elozor and R’ Chezkeya finding a snake on their path and R’ Elozor stopped R’ Chezkeya from killing unnecessarily the snake. Meforshim (ibid) debate whether that was only because it happened in the desert or if that snake was created for a specific needed purpose (See Kaf Hachaim and Maareches Hamishna Berura 2: p. 552) Horav Shlomo Miller’s Shlit’a opinion is similar.