This will create a bookmarklet that creates a card about the current page on a list of your choosing. The name of the card will be the title of the page, and the url will be in the card's description.
You will first have to authorize it to use your Trello account. Then, pick the board and list you want the cards to appear on, and drag the link to your bookmarks.
You can try it here.
The code is here.