Jenny of [The Shifted Librarian] found a great resource for sifting through your reading aggregator files and adding a search for your readers too:

Drat - I don't have time to add this to my site tonight, but I will next week. Micah Alpern has made it even easier to add his Search Blogs You Read engine to your site! Now called the Trusted Blog Search, you can use his mighty-fine, fill-in-the-blank wizard to produce code to copy and paste into your template. Excellent job, Micah! [Add the Trusted Blog Search to Your Site! The Shifted Librarian]

and another great rss searcher (blogs only)  that is improving minute by minute: Roogle [The Fuzzy Group]