vim

I edit a few different types of files with a few different indentation styles. Now, my favorite text editor is vim, and that supports using a config file to set your indentation style, but since I use a few of them, one config file won't work for me. Now, I'm sure you could also set a different style per filetype -- for example, python indents two spaces, C uses tabs displayed as four spaces. But that doesn't work, because different projects sometimes choose different styles, even though they use the same type of file.