The open architecture of Mozilla + Firefox has been a great driver of innovation over the last few years - just when it looked like IE 6 was going to be as far as the browser would go, the explosion of Firefox has kickstarted the browser market into one of the hotbeds of development effort again.
For those of us who remember the Browser Wars of the 90's, this excitement is tempered by a wry smile and the occasional twinge of apprehension - for instance, although IE7 is going to support tabbed browsing, it's still not going to support full CSS 2.0 - but how can anyone fail to appreciate the power, elegance, and sheer all-round damn-fine-ness of something like the IE Tab View plugin for Firefox ?
Definitions of A Brilliant Idea are many and varied, but my favourite is "something which doesn't exist but should" - and this definitely falls into that category.
All it does is use the IE plugin to render a Firefox tab. So when you right-click on a link, as well as options for "View In New Window" and "View in New Tab", you also get "View In IE Tab" - and it does just that. Plus you get a little icon on the status bar which lets you switch between the IE and Firefox rendering engines for the current page within your current tab.
Simple, effective, genius. Love it.