A great 20min talk from Rajit Manohar from Cornell, talking about self-timed (or asynchronous circuits) and their use in neuromorphic chips.

https://www.youtube.com/watch?v=AVrJRPL-e0g

Async is a perfect design style for these kinds of event driven chips, since you really don't need to run a fast clock if most of the time the circuits aren't computing anything ...