  Chameleon dark energy is a matter-coupled scalar field which hides its fifth
forces locally by becoming massive. We estimate torsion pendulum constraints on
the residual fifth forces due to models with gravitation-strength couplings.
Experiments such as Eot-Wash are on the verge of ruling out "quantum-stable"
chameleon models, in which quantum corrections to the chameleon field and mass
remain small. We also consider photon-coupled chameleons, which can be tested
by afterglow experiments such as CHASE.
