Okay so I suppose I am on a kick right now to share all my productivity tips (See the post on creating quick create scripts in SQL Enterprise Manager). Often I need to copy an entire line of code and paste it directly under the line I just typed. You could do something like type End > Shift > Home > CTL-C... to copy that line.
Or...
In the Visual Studio.NET (2003 & 2005) you can place your cursor anywhere in the line and type CTL-C > CTL-V. This will create a copy of your previous line directly under the original line along with a return after the new line!
I hope this helps.
Be sure to check out the latest podcast on Using the Ajax.NET Framework.