I'd add the following
- Baidu Translate
- Google Translate
- Microsoft/Bing Translator
- Baidu
- Ctrip - both the international and local versions as I've seen cheaper prices
- YouKu - not really indispensable but like youtube with way longer ads
- QQ music
Yea, I added three different translators but they each have their strength and weaknesses. IMHO, Baidu is best at understanding spoken Mandarin. Google is very good, but gets more confused with my girlfriends Hunan accent. Add Microsoft just for completeness. WeChat uses the Microsoft translator for text since they have an open API.