Omen by Christie Golden

This book features more Jedi going crazy on Coruscant, Luke and Ben visiting another different group of Force users (the Aing-Tii), and the appearance of a pocket of Sith, who have been stranded for millennia, and discover that instead of rejoining a galaxy ruled by Sith, they'll be reentering a galaxy where the Jedi prevail (for the most part). It felt short, and there wasn't a lot of forward progress on any front (except for the GA hating the Jedi more and more), but I'm really excited about this group of Sith coming into play.