How to start Android Kernel programming?

Question

I have 6 months experience with Android, developing simple UI-based applications. Now I want to write applications targeting the Android core Kernel. For example, I want to

Answer 1

• xda-developers
  A very awesome and very active place for anything smart smart phone related.
• kernelnewbies
  Generally good resource for starting out learning linux kernel
  (Which is what the android is built off of)
• Building Android Kernel
  Android Kernel Source
  
• Linux kernel
  Online guide to driver development among many other related topics.
  

Update

For android source code you can check out one of the following...