Vinai Kopp (of magetv fame) just released a small project with an improved cache cleaner for Magento 2, and it includes a file watcher. i.e. if you change a file that typically requires you to clean your cache to see changes, (like a controller or a layout XML file), this watcher will automatically notice and clear your cache for you. It also sounds like the watcher includes some smarts so only the caches you need to to clear are cleared, and it also includes support for the varnish full page cache.
I dislike that web development’s gotten so complicated that these sort of tools are needed, but if I was working with M2 this would be an instant install.