The one I'm actually excited about is Ruffle.rs (a Flash emulator that runs on browser) made by the Newgrounds guys, because not having to download stuff is always a plus for me. You can go to their website and try it yourself, you can watch the animation that comes embedded with it or upload a SWF and play it.
It's still an alpha so it has compatibility issues with some SWFs. But it's still interesting just to check out the technology, WebAssembly will allow some cool stuff.
@rexxilion Thanks. I differed widely from Steve Jobs on a lot of his philosophy, but on the issue of not supporting Flash, I was glad. It was non-Free software, and apparently was the cause of so many crashes and vulnerabilities. Hopefully, ruffle.rs will save us from those!