Isotonik Studios sell amongst other things, plenty of unique and imaginative Max For Live Devices. At Synthfest, they were showing of various examples of devices created by their producers for use with Ableton Live and a number of controller integrations.
We had a chat with James Waterworth who is working on a series of useful CV and gate utilities for working with DC coupled audio interfaces.
Then Ned Rush and his Visual Collection - video generation devices - people are using them for external video projection based on the Ableton session in which they are hosted.
Mark Towers and his Arcade series - generative sequencers inspired by classic arcade games which also integrate with external controllers like Push and Novation's Launchpad.
Finally, MetaFunction's Phelan Kane, who was showing our WaveJunction instrument - with 2 Oscillators, 3 filters, 5 envelopes and 5 LFOs plus a 12 slot modulation matrix. (available directly through us here)