Very interesting: Apparently there's a rumor going around that the Pope will name St. Juan de Avila a Doctor of the Church at the next World Youth Day. I have mentioned John of Avila as a likely candidate, perhaps the most likely candidate, for being made Doctor of the Church at some point (here and here).
'Doctor of the Church' is a purely liturgical title given to universal teachers. The word 'Doctor' here means 'teacher'. Because it is a liturgical title, it is not given to martyrs (whose status as martyrs or confessors would typically override their status as doctors for liturgical purposes). It has become increasingly important as a sign that the person in question is an excellent source for understanding the Catholic faith, because to have the title is exclusive to (1) saints in the universal calendar who (2) were doctors (i.e., theological teachers) and who (3) have left theological writings that (4) are of high quality and broad application. Currently there are thirty-three individuals with the title. John of Avila, if he really is named, would make the the fourth person from Spain on the list; World Youth Day 2011, of course, is in Madrid in a couple of weeks. If he is named, I'll have to update my Doctors of the Church post.
There's a lot to like about John of Avila in particular; his correspondence is excellent, and filled with good practical advice.