Hi Rohit, yes, the points are the same, but your graphics looks definitely better! I should have plotted al least no lines at all, just points ...

Hi Rory,

One way to do it (not particularly efficient)

distributeKey[key_][assoc_] := 
 KeyValueMap[<|KeyTake[assoc, key], <|#1 -> #2|>|> &, KeyDrop[assoc, key]]

distributeKey["a"] /@ assoc // Flatten

(* 
{<|"a" -> 5, "b" -> 7|>, <|"a" -> 5, "c" -> 9|>, <|"a" -> 5, 
  "d" -> 8|>, <|"a" -> 3, "b" -> 12|>, <|"a" -> 3, 
  "c" -> 14|>, <|"a" -> 3, "d" -> 17|>, <|"a" -> 8, 
  "b" -> 0|>, <|"a" -> 8, "c" -> 5|>, <|"a" -> 8, "d" -> 32|>}
*)

distributeKey["date"] /@ ds // Flatten

(*
{<|"date" -> "01/06", "a" -> 140.|>, <|"date" -> "01/06", "b" -> 868.|>, 
 <|"date" -> "01/06", "c" -> 450.|>, <|"date" -> "01/06", "d" -> 593.|>, 
 <|"date" -> "01/06", "e" -> 233.|>, <|"date" -> "01/06", "f" -> 457.|>, 
 <|"date" -> "01/06", "g" -> 105.|>, <|"date" -> "02/06", "a" -> 139.|>, 
 <|"date" -> "02/06", "b" -> 836.|>, <|"date" -> "02/06", "c" -> 477.|>, 
 <|"date" -> "02/06", "d" -> 528.|>, <|"date" -> "02/06", "e" -> 268.|>, 
 <|"date" -> "02/06", "f" -> 472.|>, <|"date" -> "02/06", "g" -> 119.|>, 
 <|"date" -> "03/06", "a" -> 117.|>, <|"date" -> "03/06", "b" -> 820.|>, 
 <|"date" -> "03/06", "c" -> 409.|>, <|"date" -> "03/06", "d" -> 563.|>,
 <|"date" -> "03/06", "e" -> 298.|>, <|"date" -> "03/06", "f" -> 461.|>, 
 <|"date" -> "03/06", "g" -> 116.|>}
*)

My system (Mathematica 7) does not understand your assoc. So I tried this

assoc1 = {{"a" -> 5, "b" -> 7, "c" -> 9, "d" -> 8},
  {"a" -> 3, "b" -> 12, "c" -> 14, "d" -> 17},
  {"a" -> 8, "b" -> 0, "c" -> 5, "d" -> 32}}

ff[x_] := Table[{First[x], x[[j]]}, {j, 2, Length[x]}]

ff[assoc1[[1]]]

ff /@ assoc1
% // Grid