Here are some links I find interesting.

Astronomy and Physics

3D Starmaps A site full of 3D starmaps and sky catalogues

Chesterfield Astronomical Society

Fusion - Tokamak research in Europe

Institute of Physics - Professional association of physicists in the UK

Jodrell Bank - The Jodrell Bank Radio Observatory based in Cheshire, England

JPL homepage - Information and news on many past, present and proposed NASA projects

NED - The NASA Extragalactic object Database

PPARC - Funds particle physics and astronomy research in the UK

Stuart's homepage, with more links to astronomy sites than you can shake a mirror at!