Vim overview

function! <sid>Overview()
    call system('echo > .overview; for file in *; do echo "$file {{{1" >> .overview; head "$file" >> .overview; done;')
endfunction

augroup overview
    autocmd!
    autocmd BufWrite * call <sid>Overview()
    autocmd BufEnter .overview edit
    autocmd BufEnter .overview setlocal readonly
    autocmd BufEnter .overview setlocal foldmethod=marker
augroup END