Basically just grab a directory listing every 10 seconds to figure out if any new folders have been created since the last check.

This is what I've written:
alias dirmon {
  ;set up variables, create a list of folders
  var %dirB, %i = 1
  noop $finddir(C:\Temp\,*,0,1,set %dirB $addtok(%dirB,$1-,127))

  ;loop through all the tokens in dirB, see if they exist in dirA
  while (%i <= $numtok(%dirB,127)) {
    if ( $findtok(%dirA,$gettok(%dirB,%i,127),0,127) == 0 ) {
      echo new folder found: $gettok(%dirB,%i,127)
    inc %i

  ;write dirB overtop of dirA for the next run
  set %dirA %dirB