Recently Google released Web Accelerator add-on that prefetches pages based on links in the page you're viewing. This might work well in news site or something, but in a browser web application it had a negative effect. A link might be to some application function that should not be fetched automatically such as “Add Record” or “Delete”. I know it's not completely Google's fault and that there are proper ways of writing code instead of a simple hyperlink to avoid this. But the fact is many web apps are written that way and it back-fired with Google's add-on.
I think this is really a fundemantal flaw in using the browser for writing web applications. The browser never made sense to me as a web application host, as a developer you spend more time fighting the platform(s) than focusing on your own application logic.
Here at Data Dynamics we're working on something that we hope will fix that. It is very top secret now. However, rest assured that I will have a lot more to say about it in few months :)