Periodic Table
I've been experimenting with Apple's Core Data to develop new software. Here is an Mac OS X Xcode Core Data Project File for the Periodic Table. Just so you don't get disappointed, this software does not present a window with an interactive Periodic Table, although that could be a possibility at some later date. The more important idea here is to generate discussion and develop a Core Data model for the Periodic Table that is versatile and could be used in other applications down the road. Below is a rough draft for starting a Periodic Table Data Model in Xcode.
If anyone (i.e. other scientists who like to write software) is interested in helping out with this, or other related software, please let me know.