To recap: VimR, or Vim Refined, is a Mac project to bring GUI features to Vim. It has a quick open/search dialog, a file drawer, and a preview system that's great for writing Markdown.
It's available at vimr.org and was started by Tae Won Ha, but now has three more developers.
The file menu is very friendly, combining Vim keyboard shortcuts with a Mac-style file system view. You can use
hjkl to navigate, return to open a folder, and
/ to search.
The preview is also cool, although I think it only refreshes when you save the file. I thought it might be realtime because that would be harder to do with standard Vim plugins, but it still feels nice to use.
The other up and coming GUI altvim is Neovim, which received a big update in July.