Amazon Posts Higher Quarterly Profit  SAN FRANCISCO (Reuters) - Online retailer Amazon.com Inc  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AMZN.O target=/stocks/quickinfo/fullquote"&gt;AMZN.O&lt;/A&gt; on Thursday posted a higher quarterly profit, fueled  by strong international sales and its free shipping offer.