Apparently I've been using LyX since '03. I've got 300+ LyX docs
relating to teaching (notes, exams, slide shows, handouts), but this
might be a bit inflated since I put each chapter/lesson in a separate
file, rather than compiling a book. On the "scholarly output" side,
I've got something like five journal articles and a couple of
encyclopedia "chapters" (short articles) written with LyX. Plus I use
it for a few personal sorts of documents (such as my c.v.).
Other than Firefox and Thunderbird, this is probably the open-source
program I use most often. (Tied with MiKTeX, I guess.) Props to all
the developers, past and present.
/Paul