J. Talbot and Y.P. Varshni, University of Ottawa.

http://www.achilles.net/
~jtalbot/data/elements/

This page and JAVA applet from the Laser Stars site shows the line emission spectra of the light elements in gas discharge tubes.

Physics 2000 Initiative, University of Colorado at Boulder.

http://www.colorado.edu/physics/
PhysicsInitiative/Physics2000
/quantumzone/

This lavishly illustrated and JAVA-rich (and often slow) site includes a detailed storyline describinglasers, spectral lines, the Bohr atom, the patomic physics construction of the Periodic Table of the elements, and related topics. In particular, check out the animations that show the creation of X-Rays via Bremsstrahlung and K-shell knockout.

J. Talbot's Laser Stars, University of Ottawa.

http://www.achilles.net/
~jtalbot/history/

This collection of pages presents the history and operation of lasers as an adjunct to the study of natural laser phenomena in stars. There are also links to laser use in Holography at the bottom of the page.

http://www.periodic.lanl.gov/

A sophisticated online periodic table of the elements created by the Los Alamos Nuclear Laboratory.

Radiology Centennial Inc., Penn State University Department of Radiology.

http://www.xray.hmc.psu.edu/rci/centennial.html

One of the best of a number of sites celebrating the 100th anniversary of the discovery of the X-ray by Rontgen in 1895. This site describes the history and theory of X-rays, and discusses medical applications of X-rays at length.

Program 49: Atoms. Spectroscopy, and atomic models through to Bohr. A thirty-minute on-demand streamed physics lecture / animated presentation hosted by Professor David Goodstein of the California Institute of Technology as part of the Annenberg / CPB series The Mechanical Universe and Beyond.

http://www.learner.org/progdesc
/index.html?uid=42

This site requires cable modem (384K) or better speed connection to the internet and free registration with Annenberg / CPB.

A JAVA simulationfrom the National High Magnetic Field Laboratory at Florida State University.

http://micro.magnet.fsu.edu/electromag/ java/rutherford/

A very nice JAVA applet demonstrating the classic Rutherford experiment performed by Geiger and Marsdent, this applet allows one to see how the experiment supports Rutherford's solar-system-like model of the atom and refutes Thompson's plumb-pudding model.

There is a large and sophisticated site here called Molecular Experssions: Exploring the World of Optics and Microscopy that is well worth reviewing if you are interested in state of the art imaging microscopy and image analysis.