We present an overview of selected recent static compression studies of low-Z materials to megabar pressures (> 100 GPa). Dense hydrogen shows unexpected complexity as is evident from new spectroscopic transitions and unusual behaviour of the pressure dependence of the ortho-para-hydrogen conversion rate. -ice exhibits tunnelling effects in a quantum-crystal state before transforming to a statically symmetric hydrogen-bonded structure well above 100 GPa. Studies of dense simple molecular compounds reveal new chemical phenomena and pressure-induced changes in intermolecular interactions. Magnetic susceptibility experiments on sulphur to 160 GPa reveal this material to be the highest-temperature elemental superconductor measured to date.