I've been using Vim for awhile as my primary editor and when I was first starting I did a lot of poking around to see what other peoples setups looked like, so I figured I'd contribute a quick article back to the innernets with my setup.
Only one of the plugins I have installed is actually Rails specific, and the only thing OS X specific is iTerm, so perhaps a better title for this article would be simply "My Vim setup".
I use iTerm instead of Terminal.app, because iTerm supports a few things that I find improve the environment: Fullscreen, 256 color support, and xterm mouse event passing. I've played with MacVim as well a bit, but I like the ability to have terminal sessions open in other tabs.
Of course, most of the setup involves plugins, so I'll go over the ones I'm using.
NERD Commenter
While it's pretty easy to do block commenting with visual block mode, this plugin makes it even easier, and is a lot more flexible. The one thing I didn't like about i was it's huge amount of default key mappings, which are fairly easy to disable - I set it up to just have three mappings, Toggle, Comment, and Uncomment in .vimrc
let NERDCreateDefaultMappings=0 let NERDSpaceDelims=1 map <Leader>/ NERDCommenterToggle map <Leader>[ NERDCommenterAlignLeft map <Leader>] NERDCommenterUncomment
NERD TRee
This gives you a left buffer which can be quickly toggled to browse your file system, and lots of options on how to open files (in split windows, tabs, preview buffers, etc). It's a lot nicer than the built in browser, and more convenient with the ability to toggle it in a small left buffer. I prefer this to the Project plugin, but it's worth a look as well if you are after this type of functionality. Unlike his other plugin, this one does not come with a bunch of default mappings so i mapped 'Toggle' to tt: map tt :NERDTreeToggle<CR>. I find this works well, as it's easy to quickly call it up, open a file, and then send it away again.
SimpleFold
This is a really simple one, it gives you a simple keypress (<Leader>+f) which folders everything in the file, and a command to fold everything matching a regular expression. I don't use it that often, but does come in handy occasionally.
FuzzyFinder/FuzzyFinderTextmate
This is a great plugin which gives the functionality that apparently TextMate has with cmd+t, which is to quickly find a file based on a auto completing search dropdown. Great for quickly opening files without having to type the full path, or if you are looking for something.
Git.vim
This provides a bunch of commands to work with Git from within Vim, but I mostly use it for displaying the current branch in my status line:
set laststatus=2
set statusline=%<%f%m%r\ (%l:%c)\ %=\ %{GitBranch()}\ %h%w%y
The GitBranch() part just shows the current branch. (If you use Zsh, I wrote a post awhile back on how to put it in your prompt, too)
Rails.vim
This does all kinds of fun stuff, and if you are working on Rails projects you should install this. Even if just for the extended syntax highlighting... Some of the more useful commands it provides are gf (jumps to a file based on where your cursor is, kind of like ctrl+click in Netbeans or similar editors), :A (Jump to alternate file, spec or test and back from a file), and :R (Jump to related file, views, etc.), Partial extraction, and a lot more.
Surround
This is a simple plugin that provides a bunch of commands for working with surrounding characters - Easily change, add, or remove quotes, brackets, etc from words, lines, selection, paragraphs, etc. Not much else to say, but it's a time saver when you need it!
Not that a screenshot of Vim is very exciting, but here is one anyway - you can see the status line with the git branch (on the right) and the NERD Tree buffer on the left.
Hope this helps somebody, and If there are any other Vim users reading this, I'd love to hear any feedback on other Vim tricks or favourite plugins!