Prior to 1958 no player had ever walked and struck out 120 times in times in the same season. (In fact there had only been 8 seasons of 120 SO to that point.) In 1958 Mickey Mantle  became he charter member of the 120/120 club with 120 strikeouts  and 129 walks. Over the next 28 years only  Jimmy Winn (1969),  Frank Howard (1970) and  Mike Schmidt (1983) would match Mantle's feat.  However, since 1987  there have been 16 such seasons  by 9 players, including 4 by Jim Thome and multiple seasons by Jack Clark, Jeff Bagwell, Mark McGwire and Adam Dunn. Dunn was the only player to do it in '08.

Here are the members of the 120/120 club:

  Cnt Player            Year  SO  BB Age Tm  Lg  G   PA  AB  R   H  2B 3B HR RBI IBB HBP  SH  SF GDP  SB CS   BA   OBP   SLG   OPS  Positions
 ----+-----------------+----+---+---+---+---+--+---+---+---+---+---+--+--+--+---+---+---+---+---+---+---+--+-----+-----+-----+-----+---------
    1 Adam Dunn         2008 164 122  28 TOT NL 158 651 517  79 122 23  0 40 100  13   7   0   5   7   2  1  .236  .386  .513  .899 *793/D
    2 Bobby Abreu       2006 138 124  32 TOT ML 156 686 548  98 163 41  2 15 107   6   3   2   9  13  30  6  .297  .424  .462  .886 *9/8D
    3 Jason Giambi      2003 140 129  32 NYY AL 156 690 535  97 134 25  0 41 107   9  21   0   5   9   2  1  .250  .412  .527  .939 *3D
    4 Jim Thome         2002 139 122  31 CLE AL 147 613 480 101 146 19  2 52 118  18   5   0   6   5   1  2  .304  .445  .677 1.122 *3D
    5 Adam Dunn         2002 170 128  22 CIN NL 158 676 535  84 133 28  2 26  71  13   9   1   3   8  19  9  .249  .400  .454  .854 *739/D
    6 Jim Thome         1999 171 127  28 CLE AL 146 629 494 101 137 27  2 33 108  13   4   0   4   6   0  0  .277  .426  .540  .966 *3D
    7 Jeff Bagwell      1999 127 149  31 HOU NL 162 729 562 143 171 35  0 42 126  16  11   0   7  18  30 11  .304  .454  .591 1.045 *3/D
    8 Mark McGwire      1999 141 133  35 STL NL 153 661 521 118 145 21  1 65 147  21   2   0   5  12   0  0  .278  .424  .697 1.121 *3
    9 Mark McGwire      1998 155 162  34 STL NL 155 681 509 130 152 21  0 70 147  28   6   0   4   8   1  0  .299  .470  .752 1.222 *3
   10 Jeff Bagwell      1997 122 127  29 HOU NL 162 717 566 109 162 40  2 43 135  27  16   0   8  10  31 10  .286  .425  .592 1.017 *3/D
   11 Jim Thome         1997 146 120  26 CLE AL 147 627 496 104 142 25  0 40 102   9   3   0   8   9   1  1  .286  .423  .579 1.002 *3
   12 Jim Thome         1996 141 123  25 CLE AL 151 636 505 122 157 28  5 38 116   8   6   0   2  13   2  2  .311  .450  .612 1.062 *5/D
   13 Tony Phillips     1996 132 125  37 CHW AL 153 719 581 119 161 29  3 12  63   9   4   1   8   6  13  8  .277  .404  .399  .803 *7/843
   14 Mickey Tettleton  1992 137 122  31 DET AL 157 654 525  82 125 25  0 32  83  18   1   0   6   5   0  6  .238  .379  .469  .848 *2D/379
   15 Jack Clark        1989 145 132  33 SDP NL 142 593 455  76 110 19  1 26  94  18   1   0   5  10   6  2  .242  .410  .459  .869 *39
   16 Jack Clark        1987 139 136  31 STL NL 131 558 419  93 120 23  1 35 106  13   0   0   3   5   1  2  .286  .459  .597 1.056 *3/9
   17 Mike Schmidt      1983 148 128  33 PHI NL 154 669 534 104 136 16  4 40 109  17   3   0   4  10   7  8  .255  .399  .524  .923 *5/6
   18 Frank Howard      1970 125 132  33 WSA AL 161 706 566  90 160 15  1 44 126  29   2   0   6  23   1  2  .283  .416  .546  .962 *73/9
   19 Jimmy Wynn        1969 142 148  27 HOU NL 149 653 495 113 133 17  1 33  87  14   3   2   5   5  23  7  .269  .436  .507  .943 *8
   20 Mickey Mantle     1958 120 129  26 NYY AL 150 654 519 127 158 21  1 42  97  13   2   2   2  11  18  3  .304  .443  .592 1.035 *8

Jack Clark's seasons both stand out.  In 1987 he managed to do 130/130 without the benefit of 600 PA. In 1989 Clark once again  had more than 130 Ks and BBs,  but this time with only 110  hits.

Also of note were Jeff Bagwell's 1999  and McGwire's 1998 seasons in which they added more than 120 runs and RBI to their walks and strikeouts.