Filter Forge is – by quite a margin – the most powerful plug-in we've looked at here. That's because it's a tool for creating plug-ins, both generative texture-creation tools and effect filters.
“I needed rock textures and instead of the usual day it takes me to make one, I was able to make 20! Again – applause to you all.”
“Chief among my pleasures is Filter Forge, which I've been ranting (positively) and raving (voraciously) about ever since it entered my life.”
Resident Enlightenment Manager Linden Lab, makers of virtual world Second Life