Databases

CODATA Key Values of Thermodynamics
http://www.codata.org/resources/databases/key1.html
Compilation of internationally accepted values for the thermodynamic properties of key chemical substances, proposed by the Committee on Data for Science and Technology (CODATA).

CRC Handbook of Chemistry and Physics
http://www.hbcpnetbase.com/
Data on Thermochemistry, electrochemistry, and kinetics (section 5) and Fluid properties (section 6). Data may be accessed after purchasing a personal or institutional subscription.

F*A*C*T Thermochemical Database
http://www.crct.polymtl.ca/fact/index.php
Very useful database of thermochemical properties that also includes utilities for Gibbs energy minimization calculations.

NIST Chemistry Webbook.
http://webbook.nist.gov/chemistry
Contains databases of thermochemical properties of a large number of substances.

Tutorials

Second Law of Thermodynamics
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html#c1
HyperPhysics page on the second law.

Second Law of Thermodynamics
http://theory.uwinnipeg.ca/mod_tech/node78.html
A more "wordy" tutorial on the second law.

First and Second Law
http://www.columbia.edu/itc/chemistry/chem-c140498/jack/ch11.html
A song about the laws of thermodynamics by Flanders and Swan.

Entropy and the Second and Third Rules
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch21/chemical.php
Introduction to entropy.

The Second Law
http://www.chem.uci.edu/undergrad/applets/bounce/bounce.htm
A simulation of a bouncing, heatable box that illustrates The Second Law of thermodynamics. By manipulating the parameters of the simulation you can illustrate a number of fundamental facts about energy flow.

Maxwell Relations
http://scienceworld.wolfram.com/physics/MaxwellRelations.html
Derivations of the Maxwell Relations.