Ah, Opera! My favourite browser has been recently update to version 11. There are lots of new beautiful features, like Presto 2.7 engine, improved HTML5 support, tab stacking, mouse gestures visualisation^[1], smart address field, Extensions and much more.
Opera 11 has been officially out for just two weeks, and there are already 300 Extensions (also known as "Add-ons" in Firefox and (surprise!) "Extensions" in Chrome) available!

So, the number of extensions is growing rapidly. But how can one benefit from an extension? Well, if you are a user-js geek, first, think of Opera extensions as of always up-to-date 3^d party user-js scripts. The provided browser communication API for managing windows, tabs, toolbars, icons etc. makes a complete picture. Yet, a user-js is just a script that can be initially triggered at various page loading stages. Every extension, for starters, has it's own process constantly running in background... But why discuss technical issues? I'm sure a geek can find a way to create an extension in 30 minutes. (Hopefully all geeks have followed that link :)

I believe, there is no need to explain, what YouTube is. The widely-used video hosting service already got it's fair share of Opera extensions. Would you like to find out what features these wonderful extensions are capable of?