SpreadServe uses Tornado
SpreadServe's RealTimeWebServer is built in Tornado. Spreadsheets loaded into SpreadServeEngine instances are projected into browsers using Tornado. Server side recalcs are pushed to the browser using web sockets.
papaver uses Tornado
setup an api for a client with tornado backend. incredibly fast and lightweight. unfortunately breaks down when using third party libraries which block internally.
Banyan uses Tornado
Tornado with Async/Await coroutines provided in Python 3.5 make up for an excellent stack for a micro-service.
Kalibrr uses Tornado
We use Tornado as our websockets server, using SockJS (an alternative to socket.io).