I’ve written about it here before, but here are a few links about wabi Sabi:
http://phpwiki.sourceforge.net/phpwiki/WabiSabi
http://www.stonebridge.com/wabisabi.html
And a couple of books available:
http://www.amazon.com/exec/obidos/ASIN/0879058498/
http://www.amazon.com/exec/obidos/ASIN/1586850105/