Most news aggregators like
FeedDemon have a feature that allows you to just insert the url to the website and the software detects the url to the xml file on it self and you don't need to find out where exactly the newsfeed is.
This little code snippet (its a template mod for vbulletintemplates.com) tells the software where the newsfeed is. It's really handy.
Here's a practical demonstration:
Imagin vbulletin.com has this 'hack' installed. Now you install FeedDemon and you only need to enter
www.vbulletin.com/forum and FeedDemon automatically finds out where the newsfeed is.