[Koha] Reports Documentation...

This is more of a "koha workday" request more than anything... What I (as the IT admin dude, NOT a librarian) would LOVE to have, is some sort of documentation on building custom reports, some simple examples...what tables/fields are most usable in the DB... It would be really trivial(IMO) to create some custom SQL queries as requested by the Librarian, when they ask "How come there isn't a report that does XYZ?" Then again, this might already be out there(along with a bunch of reports and I just haven't found them yet) --Huck