Editor's note: This LISP program was updated to v2.1 in April 2011. The table format is completely different, as it uses separate columns for each unit, and it has been modified to use a CSV file type.
Juan Villarreal has submitted a great LISP program named AC_Area-Calc. This routine allows you to select any number of closed objects in AutoCAD, such as polylines, circles, splines, etc., and a summary table will be constructed to report the area of each object and the total area overall. Start by loading the LISP file, then type in the command AC. The first prompt allows you to filter the selection by entity type, if you like. After you make your selection, a dialog appears with many options for area conversion, precision, and type of output. You can output the table to a table entity in AutoCAD, lines and text in AutoCAD, a TXT file, or a Microsoft Excel file. The first two options also allow you to use fields in the table so that if the closed areas are edited, the area labels in the table will stay in sync. Although there are not a lot of comments in the code, this is a good example of creating a dialog at run time, and how to create fields using LISP.