An amazing color self-portrait photo of Curiosity standing on Mars, on sol 84 (October 31, 2012). The photo is a mosaic of images shot with MAHLI, the camera on the end of the robotic arm. Although MAHLI is mostly intended as a tool for viewing soil and rocks up close at microscopic resolution, it can focus out to infinity so can be used to photograph things at any distance.
MAHLI is located on the turret at the end of the robotic arm. That turret can be seen reflected in two places on the rover's "head". The large primary mirror of the ChemCam telescope (the Cyclopean eye in the top of the mast) contains an upside-down image of the turret. The lens on one of the Navcams reflects a mirror image of the turret.
A preliminary version of the same portrait is projected slightly differently, resulting in less distortion of the rover but significant curvature of the horizon: