I have Feng Office installed here – mathster.com/office (demo here – http://www.opensourcecms.com/scripts/details.php?scriptid=439&name=Feng%20Office). NB Calendar in demo needs to be enabled via admin panel I want to tailor it for use with teachers and need a timetable module adding to it… (Budget: $30-$250 USD, Jobs: MySQL, PHP)
