Although this is an improvement made in the core AutoCAD product for 2012, I thought it was a pretty nice little improvement for Civil 3D 2012 as well. Simply start typing a command on the command line and Civil 3D will “suggest” a list of commands after the default time of 0.3 seconds. This default time can be edited as well as other options by right clicking in the suggestion list. So if you are a command line wiz, you can edit this to make the default time to appear much longer so you never see the suggestion list.
Although it could be intimidating when typing an “AEC…” command it can help you narrow down the command you are looking for by providing you with some suggestions. I know I find myself sometimes saying “I know it starts with ____”, now Civil 3D/AutoCAD can help me jump start my memory.