RSS Aggregator
An aggregator or news aggregator or feed reader is client software that uses a web feed to retrieve syndicated web content such as weblogs, podcasts, vlogs, and mainstream mass media websites, or in the case of a search aggregator, a customized set of search results.

Functions
Aggregators reduce the time and effort needed to regularly check websites for updates, creating a unique information space or "personal newspaper." Once subscribed to a feed, an aggregator is able to check for new content at user-determined intervals and retrieve the update. The content is sometimes described as being "pulled" to the subscriber, as opposed to "pushed" with email or IM. Unlike recipients of some "pushed" information, the aggregator user can easily unsubscribe from a feed.

The aggregator provides a consolidated view of the content in a single browser display or desktop application. Such applications are also referred to as RSS readers, feed readers, feed aggregators, news readers or search aggregators.

The syndicated content an aggregator will retrieve and interpret is usually supplied in the form of RSS or other XML-formatted data, such as RDF/XML or Atom.

Implementation

An RSS Aggregator can be developed in two ways

1. Online version
Online versions of this type of software can be developed using J2EE, .NET, PHP etc

2. Desktop Application
Desktop Application of this type can developed in .NET of JAVA.

In both version what we need is a bit of knowledge in xml parsing.

We use mySQL database to cache the pulled data so can avoid a large bandwidth usage and will synchronise the cache with the orginal version with periodical checkings.