Sign Detective app for iPhone and iPad
If you find a wrongly written sign, you can submit your discovery findings so that the sign can be corrected. As you move about the city, when you encounter a faulty or incorrect sign, take a picture of it and record the location of the sign.
When the incorrect sign is submitted, it will be displayed online. You can get "Beijing Points" for each error you find, which can be exchanged by gifts from eBeijing. Using the mobile tools provided, you can participate with other people in Beijing in searching for signs that are incorrect.