Chemistry 

In addition to such standard information as atomic number, weight, density, volume, and radius, this periodic table site also gives melting and boiling points, information on appearance and characteristics, and much more.

The American Chemical Society provides an interactive table which includes enthalpy of fusion, vaporization and molar heat capacity.

A periodic table, containing critically-evaluated data on atomic properties of the elements from the National Institute of Standards and Technology. The handout is available online in two formats (PDF & TIFF), and is suitable for high-resolution color printing for desk or wall-chart display.

An enhanced periodic table with extensive background information on each element.