Buboflash од Piotr Wasik, the author of Buboflash

Buboflash turns what you read on the web into flashcards you will remember.

SELECT, THEN CHOOSE
Select a passage on any webpage and a small bar appears beside it. Annotate keeps the passage. Flashcard… makes a question-and-answer card from it, with both sides editable before you save. Occlusion… blanks out the words you choose, for a fill-in-the-gap card.

YOUR PAGES REMEMBER
Come back to a page and the passages you annotated are highlighted where they are. Hover over one to see its annotations and cards; click to keep them open, edit them in place, or add them to your reviews.

THE SIDEBAR
Open the Buboflash sidebar to see every annotation on the page, how far each one's cards have been learned, and jump to its passage.

BOOKMARKS
Mark the place where you stopped: choose Bookmark on the selection bar, Bookmark here in the right-click menu, or press Alt+R. A small flag marks the place, with room for a note; Alt+G takes you back to the last one. The sidebar lists the page's bookmarks, and buboflash.com lists them all.

REVIEWS, SCHEDULED FOR YOU
Buboflash brings each card back when you are about to forget it, and the popup tells you how many are due today. You review on buboflash.com; the extension is how your reading gets in.

YOUR BROWSING STAYS YOURS
While the extension is switched off, or you are logged out, it sends nothing about your browsing. Switched on, it sends the address of the page you are on — never the page itself — so that it can show you your highlights there. Search engines' results pages and Gmail are skipped before anything is sent. The privacy policy sets out every detail.

You need a Buboflash account: sign up at buboflash.com, and tick "Log me in automatically" when you log in — the extension relies on it.