I would highly recommend any and all of Christian Eichhorn's Mörk Borg supplements - they all have fantastic layout and art, creative content that adds new systems and creative twists on existing ones, and capture the brutal and beautiful feel of the core book.
Purgatory is a great pick-up if you're looking to add some overall variety to your sessions, as it includes a wealth of new classes and skills, a Village Generator, and D100 Encounters. Like a few of Christian Eichhorn's offerings, Purgatory also includes a small Dungeon (Cult of the Knotted Snake), and campaign (Purgatory) with some fresh mechanics to mix things up.
Enjoy Purgatory? Check out Apocrypha for even more unique gamplay supplements/additions. Want something to complement Purgatory? Check out Galgenbeck Sacrifice or Bergen Chrypt for a more campaign-focused adventure.