http://vim.wikia.com/wiki/Vim_Tips_Wiki
Your .vimrc is essentially just going to be a collection of snippets that you've found that seem to do some good. Many of mine have been taken from other people's dotfiles, from dotfile projects such as
http://skwp.github.com/dotfiles/#section-13-1
and from the sites above. Take a look at the .vimrc of people you might know on github, for example. Here's mine, it's fairly well commented:
https://github.com/russfrank/dotfiles/blob/master/.vimrc