K-2 websites
Literacy
http://www.uen.org/k-2interactives/ - A variety of fun literacy activities
http://www.lite.iwarp.com/abclinks.htm - A long list of literacy related websites.
Maths
http://www.uen.org/k-2interactives/math.shtml - Interactive mathematics games.
http://www.abc.net.au/countusin/default.htm - Counting games.
http://www.cobbk12.org/sites/literacy/math/math.htm - Mathematics activities for all areas of Maths.
3-6 websites
Literacy
http://wednesdayswithsam.wetpaint.com/page/General+literacy+websites - Find a website for any aspect of literacy.
Maths
http://www.coolmath4kids.com/ - Mathematics activities for all areas of maths.
http://www.kidsites.com/sites-edu/math.htm - A huge list of websites related to maths for kids to visit.
http://www.mathplayground.com/ - Plenty of activities related to shapes