Automatically add .gitignore files to your projects in Emacs.
Call M-x gitignore-add-template, choose a language, (e.g. Emacs or Python) and the corresponding .gitignore file will be added to your project's root.
If you already have a .gitignore file, the new ignore patterns will be appended to it.
gitignore.el automatically integrates with Magit. Just require it. If you have Magit installed, it will prompt you for a gitignore when you create a new project.
GitHub has a set of boilerplate .gitignore templates at https://github.com/github/gitignore. This modules pulls that repo into a local cache, extracts the template names and prompts you to select one. The template is then copied over.
You must have internet connection the first time you add a .gitignore (it needs to clone the repo), but after that it will work offline.