Who wouldn’t want a big red button to hit?
This nifty little gadget is the Sync2 from Mungo Enterprises lets you start and stop sequencers in sync while leaving your master clock running. This is great for live shows where you are using both hardware and software sound sources. You could keep your drum machines and hardware synths grooving along while you load up new tracks on your laptop all without having to start/stop.
More info here.