I'm more than 3/4 done with book 4, The Ebon Staff. It's a lot longer than the previous 3 books and is packed with encounters, character development, and a ton of pathos. Watch out for the ending -- it probably doesn't get any bigger than this as far as tension goes. Also, trouble is in store for one of our four intrepid adventurers.
The Ebon Staff should be out within the next month (if I get any sleep!)