Some people like tabs, some like spaces. Very few people like it when you edit their stuff and use a different method of indentation.
This plugin scans through a file when it's opened and attempts to guess which style of indentation is being used. It then overrides your preferences so that you match the style of the file.
Currently it only detects the three most common styles of indentation, tabs, 2 spaces and 4 spaces. Patches to make this plugin more general are welcomed.
cd ~/.vim git clone git://github.com/conormcd/matchindent.vim bundle/matchindent.vim
git clone git://github.com/conormcd/matchindent.vim cp -R matchindent.vim/plugin/* ~/.vim/plugin/