I found this tip from MacOSXHints.com with lets you add custom icons for file types. (I didn't like the blank icons for Word, and Excel, docs.) http://www.macosxhints.com/article.php?story=20040809000710242&query=OS%2BX%2BDefault%2Bicons%2Bfor%2Bfile%2Btypes Here's an example:
