I was testing APEX 4.0 on http://apex.oracle.com and I noticed that on Standard Reports you can add 2 types of "special" columns: Derived Column and Column Link. At first I thought this was a new APEX 4.0 feature, but then tested on a copy of 3.x noticed it was there as well! I apologize if this is old news to people but I found it to be a pretty neat feature.
The interesting thing about these columns is that you can add Derived Column and Column Link columns and it does not modify your existing SQL.
The only difference I can tell about these 2 column types is that Derived Columns don't contain the following attributes: List of Values, Tabular Form Attributes, and Column Link