Anyone want to write a browser engine that skips all the modern BS and just does a good job delivering mostly-static webpages?This is one thing I wish more people would try (as I am), and quite honestly don't think is as hard as the big browser vendors make it out to be; my view is that the complexity in mainstream browser engines appears mainly based on how they were designed and implemented, and not as a consequence of the web standards they need to implement. The massive numbers of abstraction layers certainly contribute, as is the notion that everything should be extremely flexible and extensible (Web standards don't change all that often, and when they do they tend to do so incrementally.) It would certainly be interesting to see the limits of how simple (in terms of lines of code, binary size, etc.) and/or fast you could make a web browser and still e.g. have it pass Acid2, which probably makes it quite usable for much of the non-webapp part of the Internet.
text, images, video, audio, animations, 3d graphics, etc.
One only has to look at demoscene productions to see that providing a rich multimedia experience doesn't necessarily require all that much in the way of computational resources, and that's partly a reason why I believe web browsers could be made vastly more efficient than the norm today.