I am currently in the process of working on some of the musical web enhancement material for Mitarra. As Kosala mentioned in a few of the book announcements, the book will include both an audio component, as well as a musican enhancement - sortof a small bonus soundtrack inspired by, and appropriate for the game. I'm working on that in addition to the mechanics editing for the book. Runestones (for which I served as both mechanics and content editor) just came out and seems to be selling quite well.
As for previous work with Silven I've written (or co-written) Curses!, The Pun is Mightier than the Sword, and NPCyclopedia: Psionics. I have done the mechanics editing for Runestone, The Lutrins, Sarkuvans, and Mitarra: Cave of Crystals. I've done content on Runestones and was the production director of NPCyclopedia: Psionics. I've also written numerous articles for the Trumpeter.