MARKUS is an on-line tool that allows users to upload a file in classical Chinese and tag personal names, place names, temporal references, and bureaucratic offices automatically, and that’s just for starters. It looks powerful and helpful; check it out here. Hilde de Weerdt describes some recent updates to MARKUS here.
It can also tag the keyword list provided by the user. For people in intellectual history or Chinese thought, you can mark up all the concepts and then do a network analysis to see different relationships among concepts in one text and then compare it to another text. If the texts have a temporal tag, you can also do chronological analysis.