Some more resources for those looking for open source search components: Search Components Online has some great lists, including an exhaustive list of filters based on an article by New Idea Engineering called Where Have All The Filters Gone? Filters in this case are defined as components that extract plain text and metadata from file formats, i.e. Adobe PDF or Microsoft Word.
Another more general list of search engines and technologies can be found at SearchTools.com, although parts of this are a little out of date.
