Nintendo's Japanese Youtube channel has a handful of new costumes on display for Super Mario Maker. Activated by placing a question mark mushroom, these new costumes make Mario look like Birdo, an Excitebike and Captain Toad. As this comes from the Japanese channel there's no word yet on if these are coming stateside but I would expect NOA will have an announcement soon.
These little bonuses are fun and I'm glad Nintendo is supporting the game with DLC. I just hope a much bigger, more feature-rich update is coming sometime next year.