Great Markdown Previewer for a Vim User

As a Vim user, Marked 2 is great for previewing Markdown documents. The GitHub style is great to preview what a README.md or other Markdown file will look like in its code repository. Some of the features I really like are :

1. Being able to choose either MultiMarkdown or Discount (GitHub’s parser).
2. Being able to validate all external URLs from a single command.
3. Being able to select whether or not line breaks are retained.

mdrcw about Marked 2 - Markdown Preview