Interesting Stack Exchanges

As I discovered recently, stack exchanges can be pretty fun, informative (and time consuming!) way to discuss issues related to machine learning. Here are some relevant ones I found

• Statistical Analysis
  
• Math
  
• Natural Language Processing
  
• High-level math (non-research level questions will be closed)
  

There's also stack exchange for Machine Learning and Computer Vision that are in proposal phase. Any interesting ones I missed?

Machine Learning stack exchange is right now undergoing definition. Please go and vote on interesting questions to help define it as a research-level discussion forum