Looking for MSDS sheets?  Flinn is a good start:
http://www.flinnsci.com/search_MSDS.asp

If you need word processing, spreadsheet, or presentation software, try Open Office (it's free!): http://www.openoffice.org

A great drill-and-practice website (especially for significant figures):

http://science.widener.edu/svb/tutorial/index.html

An interactive, on-line periodic table:
http://www.webelements.com/

Two Miss Gurganus-typed periodic tables:

With names

Without names

Lost your solubility chart or activity series?

Looking for chemical structures?

Try http://www.emolecules.com, type in your compound, and choose "Text Search."  You can then save the structure as a picture!

All you ever wanted to know about the periodic table:
http://www.chemistrycoach.com/periodic_tables.htm

Another periodic table:
http://www.lenntech.com/periodic-chart.htm

See the orbitals as animations here:
http://www.uky.edu/~holler/html/orbitals_2.html
http://wine1.sb.fsu.edu/chm1045/notes/Struct/Orbitals/Struct06.htm
http://www.adi.uam.es/docencia/elementos/spv21/sinmarcos/elementos/orbitalf.html
http://www.wellesley.edu/Chemistry/chem120/ligandfieldimages.html
http://www.bcpl.net/~kdrews/mtas/modern.html#MTASIndex