Flash, Unity, Java, Silverlight, and many others, they all aimed the same - enhancing the Web - but in the end, there are only few situations where they are really useful, for films and some features like resumable file uploads or tcp-connections, mostly they are just used for stupid design-enhancements, and for games.
These little Browser Games have become the main topic of some websites, and seems like there are quite a few people who are making money with advertisements with them. There are so many of them. And they are so addictive - see xkcd:
And there are not only minigames. Even old games like Links Awakening
can be played online.
), using the ImpactJS Game Engine
(which has a nice little game on their website).
Currently, these games are mostly small and not that time-consuming, which is, as far as I see, the reason why they are so addictive. It is a world where you can still create simple games easily, and still, games have to convince the player by their idea rather than by their graphics.
On the other hand, maybe this will be the start of a new generation of portable games. Looking at some previews, the stuff that can be done with it is not that bad, compared to some games that are only slightly older. With some optimizations, maybe the advantages of having a larger user-base, not being addicted to another company, and - above all - a better control about the copies of the own game (in the end, large parts of the game are open source, but can still made dependent to the connection to a server), will make it an alternative for game developers.