Here is the comparison chart of the cams, mainly SLCDs (spring-loaded cam devices), in 2015, from various manufactures. Most of the major cams are listed here, and it may well be the best visual chart of this kind.

The horizontal scale is precisely logarithmic. The colours are of each cam (the white colour is adjusted to light gray for an obvious reason). Weight [g] and breaking strength [kN] are displayed, too. For DMM 4CU/3CU and Metolius TCU/Power-Cam, they are listed in the same rows, because their colour and size-ranges are identical to each other with the differences in the weights presented. All the data are directly taken from the respective manufacturer's website in July 2015; i.e., the cam range etc are the catalogue specification. When two pairs of camming ranges are available in the catalogue, that is, range recommended to use (without overcamming or undercomming) and physical range, the latter is used (most manufacturers provide only the latter anyway). Therefore, the maximum cam size in each box is practically unusable, as it is too undercammed.

For printing out, PDF format is available in the best quality (vector image and only 25kB).

Note that in Britain when guidebooks say, for example, Friend #3, it usually refers to the old Wild-Country Technical (or Forged) Friends. DMM 4CU (3CU) are identical to the size and numbering.

For your reference, Clyde's Climbing Cam Charts is the most complete table I know, which includes the cams that are not made or sold any more.