Fermilab - The homepage of the Fermi National Accelerator Laborator contains information about the particle accelerators and other experiments at the lab.
Institute of Physics - Contains a ranges of journals and articles as well as a section for children to play physics related games and take part in other interactive revision.
Physlink - Physics news site with a large focus on community. Has a newsletter, discussion boards and a chatroom. Also has many other resources such as games as well as an education section.
PhysOrg - Has the latest news in physics as well as articles on many different arguments. Focuses on mostly abstract physics like nanotechnology. Also have a discussion board.
All About Circuits - Offers an extensive guide to the workings of circuits and electronics. Presented in chapters and volumes. Also has a discussion forum.
Contemporary Physics Educational Project - Websites who's aims are to "present the current understanding of the fundamental nature of matter and energy, incorporating the major research findings of recent years."