One of the new commands in AutoCAD 2011 (and its verticals) is ADDSELECTED. This command will create a new object based on the object type and properties of a selected object.
You could do something similar in the past by creating a tool palette command. For example, you might create a tool palette button to draw a line on a certain layer, with a certain linetype. The difference with the ADDSELECTED command is that you are copying the properties from an existing object in the drawing.
Why not just copy the object you might ask? Suppose you have a circle and you want to create one just like it but smaller. You could copy the circle and then scale down the copy, or use the ADDSELECTED command, pick the original circle and then finish off the copy by specifying the radius. There are cases for both methods.
Where I have found ADDSELECTED to have a great deal of value is in creating hatch objects. Say you are working in a drawing where there are multiple hatched areas and you are creating more of them. Using ADDSELECTED, not only will the layer and color of the copy match, but you do not have to know the pattern name, the scale, or the rotation angle. They will match also. Just pick the original, then select the new object to be hatched. See below.
Refer to the command reference for a list of properties. per object type, supported by this command.