The machines I log into don't always have vim, so I don't bother with customization and often fall back to vi to write shell scripts (not because it's better, but because I am fast with it). When I worked as a Unix sysadmin (in a previous life) there was one guy on our team who liked emacs over vi. He was adamant about how much better it was while most everyone else could care less and just wanted to get work done. The vi vs emacs holy war pre-dates many of the people on the site, so if you're not familiar with it think of it as similar to Mac vs PC, Windows vs Linux, "Less filling" vs "Tastes great." In other words much of it pure personal preference.
I found some good vimrc's on the web... What I currently have does the trick for basic web design and simple C++, Python scripts. I do know people that customize it a little further when they are using perl, php...
Very interesting stuff. I honestly never heard of it and just googled it. So what do you use it for once you create your environment??
Emacs and Vim are super editors. They both have large learning curves and both make you massively more productive when you can use them properly. I use Emacs for writing code in any language, but text editing isn't really the end of its capabilities. There is actually an implementation of tetris built into Emacs. M-x tetris. It's insane the things you can do with Emacs and Vim.
The most I've ever had to do was modify my scheme.vim file to support the proper indentation since the rules are different depending on whether something is a function or a macro. I also made it so the keyword 'lambda' would be replaced by the greek symbol.