K Devices just released a really awesome Max for Live delay effect. Alter Echo lets you create delays with unusual time signatures, a step sequencer, and unusual envelop shapes. I was asked to create some presets and instrument racks using Alter Echo, and I had a blast running audio through it and creating some complex rhythmic delays. Alter Echo gives you unprecedented control over delays and is a really fun sound design tool. Check out the video below and pick up Alter Echo at Ableton.com.
Holder: Amazing Spectral Audio Freezing Device
K Devices has also released Holder, a devices that allows you to freeze your sounds. Think of it like a hot rodded version of the freeze function on Live's Reverb device. I've had a lot of fun creating some nice ambient textures with it. Holder is also available at Ableton.com.