one of those tools in ministry i've used year in and out is the methodist calendar. i've used the classic spiral bound calendar many of those years. my fav details is the lectionary listings not to mention the special days listed in the classic calendar. it also fits nicely in my briefcase.
the last two years i've used the wall sized dry erase calendar which was helpful, but i never spent a large majority of my time in the office so it wasn't as helpful.