Besides a fair bit of refactoring and cleanup, I've recently added two new plugins to apt-xapian-index:
app-install
If app-install-data is installed, information about .desktop files will now enter the index.
This allows, for example, to limit query results to only those packages that contain .desktop files, which is quite useful, for example for building desktop-oriented package managers.
aliases
It reads term->aliases mapping from files in /etc/apt-xapian-index/aliases/
or /usr/share/apt-xapian-index/aliases/, and feeds them as
synonyms in the index.
apt-xapian-index ships an example alias file, to give people who know the wrong software names a chance to find the right ones:
# Aliases expanding names of popular applications
excel XToffice::spreadsheet
powerpoint XToffice::presentation
photoshop XTworks-with::image:raster
coreldraw XTworks-with::image:vector
autocad XTworks-with::3dmodel
Notice how it is possible to use index terms that happen to be Debtags tags as synonyms, which yields better results, language independence and extra coolness.