The Truth About Aggregators
The word “aggregate” means to combine. (from http://dictionary.reference.com/browse/aggregate )
An RSS Aggregator is a site which groups subscriptions all into one. Say if you wanted to look at CNN, yahoo, the weather, and entertainment news, but didn’t want to go to four different sites. You can use an RSS Aggregator to group all of these together. Compare yourself to someone that doesn’t use an aggregator. You will have more time to spare if you use an aggregator than someone who doesn’t.
The most popular Aggregators are Netvibes, Bloglines, and Google Reader.
(from http://en.wikipedia.org/wiki/Aggregator )
Almost any website can be subscribed to. Just enter the web address in the subscribe bar, or you can look for the icons – like these:

Some directories you can use Syndic8, BlogStreet’s RSS Directory, or RDF-Ticker to find feeds that suit your needs. Hope you learned something today! Try them out and have fun!