Yea, the world is going tiny displays (for movies??? nuts), but for real productive use, multiple very large monitors are required.
Many web pages, however, won’t take advantage of large displays. They use fixed absolute sizes for compatibility and most common display resolution. Thus, on a large display there is plenty of room for showing multiple pages.
This is where a Multiple Tabbed Browser Interface comes in. If it were around (I just made up the term) I could just drag a tab and dock it on the edges of the browser, reusing the large monitor space for showing multiple web pages at once. Great for web development. Sure I could open up multiple browsers, and I do, but ….
This is not the same as just having multiple tabs available, wherein one can switch to different loaded web pages or apps. That just allows single-document views. In web development, having multiple docs visible (and hopefully fancy stuff, like entangled scrolling) would be ideal.
Note that in traditional Multiple Document Interface (MDI) windows are very flexible and can lead to complexity. I’m just referring to docking behavior. The Usability arguments against MDI don’t apply to MTBI.
I wrote the above without looking to see if this is already available. It’s not on FireFox, Chrome, and IE9, that I’m aware of.
Apparently, one browser does do something similar (but not different documents, just the same split document) this:
The Konqueror browser (available for the K Desktop Environment on Unix and Unix work-alikes, such as Linux) supports multiple documents within one tab by splitting documents. In a Konqueror tab, documents can be split horizontally or vertically, and each split document can be re-split.