Most of the times I make macro / close-up photos and sometimes it's pretty hard to take shots of butterflies, grasshoppers, lizards and similar shy animals. So a true macro lens with the following specifications would be great if it's possible to make it (I'm not sure about that).
Minimum focusing distance: 100 or 150 cm
Focal length: between 60 and 100 mm, but lower could be better
Full Time Manual focusing (!)
USM for AutoFocus
Maximum magnification: 1:1 (with Extension Tubes or Extenders: 2:1)