Safety tips and detailed parental control guides for all of Microsoft's operating systems and other products
Family Online Safety Institute (FOSI)
FOSI promotes best practice, tools and methods in the field of online safety
Excellent advice for everyone, including children, regarding online threats
Lots of good info for parents and also anyone that works with children
A set of sites, each aimed at a different aged audience with appropriate safety tips
Creators of "Safer Internet Day" they have lots of great resources about staying safe online
UK Council for Child Internet Safety (UKCCIS)
Working in partnership to help keep children and young people safe online