How to get comments feed from other websites?

Any idea how to extract other websites comment and insert them into our Drupal website?

Look at this example:-

http://www.bestcovery.com/onkyo-tx-sr608-receiver?rpage=1&rsort=mosthelp...
Bestcovery run in Drupal, which module is used to extract comment from amazon.com?

http://www.google.com/products/catalog?q=onkyo+608&cid=66978931345676926...
Google get comments feed from multiple sources.

Which modules used? Your help is much appreciated.