Responsive design is cool and all. The shift from desktop to multiple screen sizes, both small and large, will continue but the problem of the increased development time associated with creating responsive designs can hurt. Especially, when you end up with a totally custom design that needs to work in 3-4 viewports.
The lastest version of Firefox, which is 10, has some fancy new features for web designers and developers. For the first time Firefox has built-in inspect element functionality for html and css. It isn’t revolutionary, but the design and functionality is pretty slick. That, and this is just the first iteration. It sounds like they have more to come with each release.