Sites

Stellar Evolution (Popularity: )
http://www.astunit.com/tutorials/stellar.htm
Stars and the Hertzprung-Russell diagram (where a star's absolute luminosity is plotted against its surface temperature).

Starclock: Stellar Evolution Software (Popularity: )
http://leo.astronomy.cz/sclock/sclock.html
Starclock is a program for DOS that animates the evolution of stars on the HR diagram.

Stellar Evolution of Solar Type Stars (Popularity: )
http://cassfos02.ucsd.edu/physics/ph7/StevI.html
The complete sequence of events in detail.

Stars Beyond Maturity (Popularity: )
http://www.arm.ac.uk/~csj/astnow.html
The evolution of stars beyond the main sequence explained in detail.

Stellar Evolution (a la Chez Stella) (Popularity: )
http://www.astrosociety.org/education/publications/tnl/49/chezstella.html
The Universe in the Classroom: Basic school lesson introducing stellar evolution metaphorically through a restaurant setting.