Two modules come to mind...one would be a new offering from G-Storm: their Gyrinx VCF, which is a clone of the Synton Syrinx filter, well known for all sorts of wild modulation capabilities with a filter set that focuses on vocal formants. And the wavefolder...Tiptop's Fold offers a nice wavefolder, dual inputs, and a suboctave generator for massive square-wave bass with its own separate output. Dirt-cheap, too!