Firefox Hacks, Nigel McFarlane Lucene in Action, Otis Gospodnetic and Erik Hatcher Mining the Web: Discovering Knowledge from Hypertext Data, Soumen Chakrabarti Peer-To-Peer: Harnessing the Power of Disruptive Technologies, Andy Oram Spidering...
If you're a proficient programmer, or simply are curious about what the code looks like for a world-class search engine, check out today's SearchDay article, How to Hack Your Own Search Engine, which is a review of a new book, Lucene in Action.
That's what Lucene in Action is all about. Lucene in Action by Otis Gospodnetic and Erik Hatcher is a thorough introduction to the inner workings of what's arguably the most popular open source search engine.