It would be useful to allow for temporary local variables in formula tools. This could make code shorter, better readable, easier to maintain and help to avoid auxiliary columns which have to be deleted afterwards.
Arbitrary example for illustration:
if Length([Col1] + [Col2] + [Col5]) > 50 then
Left([Col1] + [Col2] + [Col5], 48) + "..."
[Col1] + [Col2] + [Col5]
tmpstr = [Col1] + [Col2] + [Col5]
if Length(tmpstr) > 50 then
Left(tmpstr, 48) + "..."
The idea is that the temporary variable has limited validity inside the formula for a specific cell.