In a previous post i said that Opera is one of the few non-open source programs I use due to it’s speed, standard compliance (100% Acid test), simple yet intuitive and extremely configurable interface.
I have (at last) finally moved to Firefox, since it has become fast, secure and has this enormous set of useful plugins. Some of the plugins i use try to resemble Opera a bit :
There are some really invaluable plugins like greasemonkey, zotero and ubiquity but the coolest one i have found so far is the cloudlet search plugin. It filters Google searches by Tag or site allowing not only to narrow down your query results but also to discover very similar content!
Coolness factor : 5/5!