Ok I'm back with some news. The new version is almost done - I have added these features: image rotation (in 90° steps), horizontal/vertical flip, cropping an area that shows up in a new tab as a new image, google image search.
Right now, I am finishing a few things and by the end of the weekend, the new version should be ready.
Next version should add some sort of a Settings screen, so I can add a few basic things for you to customize. White/blacklisting is a great idea, I guess it could get annoying having to turn the whole extension off when needed...
As always, thanks for support and ideas.