Since I develop mainly in Windows, these are somewhat lacking, but it works for me.
These are heavily based on other peoples dotfiles, particularly those of Holman and Charlie Somerville.
I'm always open to suggestions!
If you want to use a global .gitignore file you will need to configure your .gitconfig file to point to file:
[core]
excludesfile = /path/to/.gitignore
See my .gitconfig as an example.