Addition of NaCl and CaCl2 to snow
Salts will lower the melting point of snow or ice.
$\ce{NaCl}$ is chosen because it is cheap.

Edited: Salt with more total ions is more effective. $\ce{CaCl_{2}}$ is the one of the most available salt with 3 total ions. $\ce{MgCl_{2}}$ is another option.
Some crude $\ce{NaCl}$ produced from sea water directly contain $\ce{Ca}$ and $\ce{Mg}$ salt and can be used to melt ice.