Thought it'd be good to have a thread discussing everyones favourite free plug-ins that they use for sound design, everyone likes free. A useful resource for everyone!
To get the ball rolling for me it has to be soundhacks Pitchdelay, play around with it long enough and you can get all kind of interesting sounds.
A favourite technique of mine when using this plug-in is to set the feedback anywhere up to 50%, copy your audio clip along the track at random intervals (assuming its a short recording) then play and just let the sound stack while tweaking the pitch/time settings.
It's often my go to plug-in when I need to manipulate a sound and bring something new from it.
Available at: http://www.soundhack.com/freeware/
What is your favourite free plug-in you use?