FAQ.How can I get the item string for a given file creator?
Feedback.

Answer: Try this function:
Example:

Sub pullNativeDocs(aCREA As string)
  Dim result as integer
  Dim m, k as memoryBlock
  Dim f as folderItem
  Dim newType as string
  Dim anIcon As picture
  Dim ofs As integer
  
  Declare Function GetFileTypesThatAppCanNativelyOpen Lib "Translation" (appVRefNumHint as Short, appSignature as OSType, nativeTypes as Ptr) as Short Inline68K("701CABFC")
  Declare Function GetDocumentKindString Lib "Translation" (docVRefNum as Short, docType as OSType, docCreator as OSType, kindString as ptr) as Short Inline68K("7016ABFC")
  
  listBox1.deleteAllRows
  
  m = newMemoryBlock(1024)
  result = GetFileTypesThatAppCanNativelyOpen(Volume(0).MacVRefNum, aCREA, m)
  if result <> 0 then
    listBox1.addRow "<Not found.>"
    return
  end if
  
  do
    if m.byte(ofs*4) = 0 then
      exit
    else
      newType = m.OSType(ofs*4)
      listBox1.addRow newType
      k = newMemoryBlock(64)
      result = GetDocumentKindString(Volume(0).MacVRefNum, newType, aCREA, k)
      if result = 0 then
        listBox1.cell(ofs,1) = k.pString(0)
        ofs = ofs + 1
      else
        listBox1.cell(ofs,1) = "(unknown)"
      end if
      
    end if
  loop
  
End Sub

Notes: Change "Translation" to "CarbonLib" for Mac OS X.