select * from foo;
 name | value 
------+-------
 foo  |   -10
 foo  |    -6
 foo  |    12
 foo  |    34
 bar  |     6
 bar  |    23
 bar  |    76
 rat  |    -6
 rat  |   -60
(9 rows)

##</code><code>##

select name, sum(value) as value from foo group by name order by abs(sum(value)) desc;
 name | value 
------+-------
 bar  |   105
 rat  |   -66
 foo  |    30
(3 rows)