----- Original Message -----
[snip]
/num      -->  $return_values[num]
// or /!  -->  $return_values.last
/*        -->  $return_values.each {|val| puts val.inspect}
               # not inspect if flag is set?
----------------------------

On second thought, you would also want to be able to use the old return
values in other expressions, and not necessarily always at the beginning of
the line (though I probably do that most frequently).  So maybe a shorter
name than `$return_values' would be best.

  irb(main):022:0> RV[12] + RV[21]
  => "hello world"

Maybe a constant would be better?  `RV' for "returned values"?  But for the
record, I still like the slash tricks from above (/12, //, /*, others?).

Chris