Open Source desktop search applications

beagle - gnome, mono

http://kat.mandriva.com/ - KDE

http://www.recoll.org - Xapian, Qt

http://pinot.berlios.de/ - GTKmm,
Xapian, affilated with BerliOS?

pyindex - python

Xapian - Implemented in C++, but with many other language bindings

lucene/pylucene - written in java, but there's a gcj+swig means of getting
to it from python.  Affiliated with OSAF.  Recent version of swig don't
work for this - 2006-01-22.

From:
http://www.let.rug.nl/~gosse/Imix/clin04_tiedemann.pdf

Amberfish: http://www.etymon.com/tr.html
  GPL, C/C++, plain text, semi-structured/XML (with nested fields),
  wild-card search, phrase search, boolean queries, relevance ranking
  DRS: very easy build.
  find ~/Maildir/ -type f -name '[0-9][0-9][0-9]*' -print | count -b |
  af -d ~/amberfish/all-mail -iCF
  Started out really fast (70+ files/second), but between 30,000 and
  40,000 files, it slowed way down.
Lucene: http://jakarta.apache.org/lucene/docs/index.html
  Apache License, Java, plain/semi-structured documents, snowball
  stemmers, phrase search, boolean queries, relevance ranking
Managing Gigabytes (MG): http://www.cs.mu.oz.au/mg/
  GPL, C, csh, plain text, images, boolean or ranked queries
Swish-e: http://swish-e.org/
  GPL, C, plain/semi-structured documents, snowball stemmers, wild
  card search, phrase search, fuzzy search (soundex, metaphone), flex-
  ible configuration (input/output, tokenisation etc), boolean queries,
  relevance ranking, Perl bindings
  DRS: swish-e 2.4.3 made short work of indexing my mail archive, but:
  1) It gave a number of seemingly-spurious I/O errors
  2) It couldn't find words that I'm certain it should've been able to
Xapian: http://www.xapian.org/
  GPL, C++, plain text, snowball stemmers, phrase search, proximity
  search, relevance feedback, wide range of boolean operators, relevance
  ranking, Perl/SWIG bindings
Zebra: http://www.indexdata.dk/zebra/
  GPL, C, structured (XML), phrase search, boolean queries, relevance
  ranking, wild-card search, Z39.50 protocoll, client-server implementa-
  ton
Zettair: http://www.seg.rmit.edu.au/zettair/
  BSD-style license, C, plain, semi-structured (TREC), phrase search,
  boolean queries, relevance ranking, summary function
  DRS: Seems to be unable to index plain text, unless you feed it plain
  text and hope it won't conflict
  with html parsing conventions.  Indexes rapidly.  It hated dangling
  symlinks, and also errored out on a file
  that didn't exist - presumably it existed when find listed it, but
  something probably renamed it.
  This was with zettair 0.6.1.