Mendeleev's Periodic Table is a marvel of an information source. So much data is packed into this fairly simple looking chart, including symbol, atomic number and mass, electron configuration, and valence. I really didn't think it could be improved upon. That is until I found this web version. Clicking on the elements brings up the element's wiki page and all the info contained therein. A sliding bar in the upper right corner shows the temperatures of transition states. You can click on series, properties, orbitals and isotopes to find further information for each element. Sweet!