Astronomy Picture of the Day http://antwrp.gsfc.nasa.gov/apod/astropix.html
Beyond Books http://www.beyondbooks.com/index.htm
Periodic Table of the Elements http://www.chemicool.com/
Math Activities http://www.aaamath.com/index.html
Zoom Astronomy (Everything that you want to know about our solar system.) http://www.EnchantedLearning.com/subjects/astronomy/
All kinds of useful sites I found at Hershey. http://www.germantownacademy.org/curtech/petcactive04/petcactive04.htm
SAT practice site for math http://www.collegeboard.com/student/testing/sat/lc_two/math1c/prac/prac01.html?math1c
Algebra Problems for SAT/ACT http://www.testprepreview.com/modules/algebra1c.htm
SAT Practice Site http://www.testprepreview.com/sat_practice.htm
Practice for the PSSA (Acrobat Reader is needed to open the practice pages.) http://www.mcsdk12.org/pssa.htm
Play Sudoku online http://www.saidwhat.co.uk/sudokus/
Graphing Calculator http://my.hrw.com/math06_07/nsmedia/tools/Graph_Calculator/graphCalc.html
Mr. Kelly's Wiki page