Get a clean board on Trello.com
The board layout on Trello.com changed some time ago. They added another column on the right side of every board. As it's a great idea to onboard new users, for existing superusers it's disturbing. The "Add a list..." button just wastes space on the screen. Especially for boards with a few columns / lists, the additional button will add a horizontal scroll bar. Which has a negative impact on the user experience.
This Chrome extension solves the problem:
1. Install the extension
2. Refresh the browser tabs with Trello boards
3. And the "Add a list..." button is hidden
More at http://manuelgruber.com/trello-clean
If you want to add new lists to your board, just go to the installed extensions (chrome://extensions/). There you can disable and enable the extension.