Databases

CRC Handbook of Chemistry and Physics
http://www.hbcpnetbase.com/
Data may be accessed after purchasing a personal or institutional subscription.

MatWeb
http://www.matweb.com/
An online database of thermochemical and rheological properties of materials of interest to industrial chemists and chemical engineers.

WebElements Periodic Table of the Elements
http://www.webelements.com/webelements/scholar/index.html
Interactive periodic table of the elements, with extensive tabulation of physical and chemical properties.

Tutorials

X-Ray Diffraction Simulator
http://neon.mems.cmu.edu/degraef/xray/
Freeware with a graphical user interface for simulation of x-ray powder diffraction of two-dimensional crystals.

Models of Solids Based on Crystal Structures
http://www.geo.ucalgary.ca/~tmenard/crystal/crystal.html
This tutorial on the structures of several mineral groups requires the MDL Chime plug-in.