Wakarukana does an excellent job of determining which Japanese anime, books, movies, and manga, are suitable to your current level.
Once you have clicked on an item, the site will provide you with 5 sentences or audio clips and ask you to select which ones you understand. Depending on your comprehension, it will determine how difficult the item you selected would be relative to your level.
As it’s a new site, they don’t yet have a ton of options, but they do provide a solid start to finding level-appropriate media. Note that each search only displays 10 results — search again and you will receive another 10 random results.
The site seems to be affiliated with Japanese Level Up.