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| Roogle is a search engine for what is called a
| "RSS Feed". An RSS Feed is an XML tagged file
| which allows a website, news site or blog
| (actually any site) to provide to the world a
| list of its current contents. RSS feeds can
| contain all kinds of information from news to
| blog / weblog posts to stock quotes and more
`----

I don't know if this has been mentioned before, but here is a search engine which searches RSS feeds. Nice.

Roogle :: RSS Search Engine