There actually is a practical application for the caps lock key: I use it to switch between English and Japanese keyboards. The light is a great indicator of the mode you're in.
Wow, as someone that switches between two language inputs(coincidentally English/Japanese actually) a lot on a variety of OS's, and never uses caps lock, I think this is a great key-binding.
It's just alt-shift if you set it up through Windows' keyboard options.
Would you be so kind to expand on how to this? And if can be apply to an Yosemite Mac OS system?