Pinned for the idea. Not sure how much I like the extension over the toilet. If were to do, vanity top should be one piece, with no cut line. Also: Consider how much the extra counter space would be needed.
Install shelves above the toilet – the wall space above the toilet is generally not employed for any use. You may use this space by installing hanging shelves on the free wall space. Just ensure to leave decent space between the toilet tank and the shelf.
Take a ladder shelf and left out the bottom 2 rows to fit perfectly over the toilet. This could make for extra storage space without looking too bulky. http://hative.com/over-the-toilet-storage-ideas-for-extra-space/