I know one thing I use everyday and its my app to let me listen to music. I you could integrate that then let people share music with each other on steem (kind of like qq music which lets you share the music into WeChat). So if someone posts a song you can just click on it and listen to it.
Also I don't know if this has been said already but I live in China currently so I use WeChat everyday. One of the best features for WeChat is WeChat pay. It lets you scan a QR code and pay anyone else who has the app. It also let's you pay bills.
Another app we use a lot would be Meituan, It let's you order food and pay with WeChat pay. You can also buy movie tickets and things like that.
Hope that helps.