More are on the way. My company is actually working on JS games exclusively, and I'm doing a talk on this very subject (I actually briefly mention EntityJS) at SXSW next month. The title of my talk is "Do Gamers Dream of HTML5 Sheep" if anyone is interested.
So how are you making money with HTML5 games? I've made a fair bit of "beer" money with Flash games, but I haven't yet found a MochiAds for HTML5 yet. In-game purchases? Selling access to a less busy server?
We aren't making games comparable to flash/arcade games, they are more similar to games you find on social networks. So, the majority of revenue comes from in-game purchases.