Below is a list of the "worst" /8 (also known as class-A) blocks
in regard to spamming, in the sense of having the largest number of
different IP address blocks that I've had to research because they
sent me spam or they are upstream from other blocks that sent me spam.
(This listing was compiled on 2002.Jul.22)
These are my highest priorities for finding volunteers to maintain
toplevel CTW nodes:

       B = first Byte 
       B     S =  count of SPEWS nnn.xxx/16 directories
       B     S    C = count of CTW records / 
       B     S    C   * = comments
    a 211   213  330  (I really need a volunteer for this node!!)
   r  212*  235  281  * A volunteer (JK) is working on taking over this node.
    a 202   193  267
   r  195*  221  250  * A volunteer (AT) is working on taking over this node.
    a 210*  194  242  * A volunteer (JH) is working on taking over this node.
   r  194*  180  233  ** A volunteer (TK) is now maintaining this node.
    a 203   219  194
   r  213   217  190
    a=APNIC
   r=RIPE

If you're not an expert at spam-complaint addresses within any of those
/8 blocks, then go ahead and volunteer for one of these others below,
except the two I'm already maintaining:

       B = first Byte of IP number, i.e. nnn/8
       B     S =  count of SPEWS nnn.xxx/16 directories
       B     S    C = count of records in my local CTW cache
       B     S    C   C = comments
  A   216   245  150
   r   62   203  147
  A   209*  225  138  * I sometimes maintain this node myself.
  A   207   201  134
 L    200   187  114
   r  217   179  102
   r  193   175   99
  A    64   212   92
  A   206   173   89
  A   204   149   75
  A    66   228   74
  A   192   119   58
  A   205    93   57
  A   198*  112   48  * I'm maintaining this node myself.
  A   199   100   45
  A    24   183   42
    a  61   193   39
   r   80   149   36
    a=APNIC
   r=RIPE
  A=ARIN
 L=LACNIC