The people over at phddata.org have a site that might be useful to teachers (but especially students); it’s a web site where you can search for currently registered dissertations on a very, very wide range of subject (philosophy, theology, and medieval studies included). This will help you find out what’s being done (much like the SIEPM’s catalog), and whether a dissertation you’re about to direct (or write) is being done elsewhere by someone! Worth a look.