Sometimes all you need is a simple periodic table...

The Chemical Touch: Lite Edition is a free and easy to use periodic table for your iPhone or iPod touch. Consisting of a simplified version of the periodic table display from the full application, it puts the masses, densities, melting & boiling points, radii, and electronegativities of the elements right at your fingertips. If you need more elemental information, touch the internet button to open the wikipedia page for the selected element.

For those who have already downloaded the full version, the only thing new here is a fancy icon for your iPhone desktop. It's free though, so if you like Neon, you can display it on your phone at no loss other than space on your screen.