Really Simple Syndication (RSS) is an XML-based format for content distribution. News, information, podcasts and weblogs (blogs) can all be published in RSS. When a new article is posted or are updated, RSS feeds can automatically notify the user. Text, images, audio (including podcasts) and video can be incorporated into RSS feeds.

Here are some free news aggregator clients (readers) you can you use when subscribing to RSS/XML feeds:

Applications
Safari (Mac)
BottomFeeder (Cross compatible)
Tristana Reader 4.5 (Windows)
News Reader (Mac/Widget)
RssReader (Windows)
Surfpack (Windows)

Online
google.com
newsgator.com
bloglines.com
attensa.com

WAP 2.0 phone/J2ME/smartphone
ywwg.com/bloggo
deliciousmona.com
freerangeinc.com
phonefeeds.com
mobile.yahoo.com