ATLAS is a particle physics experiment at the Large Hadron Collider at CERN. Starting in late 2009/2010, the ATLAS detector will search for new discoveries in the head-on collisions of protons of extraordinarily high energy. ATLAS will learn about the basic forces that have shaped our Universe since the beginning of time and that will determine its fate. Among the possible unknowns are the origin of mass, extra dimensions of space, unification of fundamental forces, and evidence
for dark matter candidates in the Universe.

ATLAS also has an online store! Amid the usual apparel is an original T-shirt designed by Alan Alda with perhaps a slightly weird quotation of "imagination is more important than knowledge." How does that square with an experimental facility? You'll also find some great images and posters plus some free downloadable stuff. Luckily, they aren't selling any leaky mugs.