A MIDI arpeggiator/sequencer device from Ian Dicke for arithmetic progression (10$). There´s more good stuff (also free) on his site.
Free Ohm Force synth (You do need to register) – Performer Edition, giving you access to all of its mother’s factory presets and some other customizing possibilities.
Regrader provides a delay effect in which the repeats degrade in various ways to provide a malevolent twist on the ears. Download for free here.