Per-tab buffers; don't use this, doesn't work.

.vimrc

" Inspired by https://vi.stackexchange.com/questions/4091/how-to-bind-a-set-of-buffers-to-a-tab
if !exists("g:WindowBufManager")
  let g:WindowBufManager= {}
endif

function! InitTabBufferList()
  if !has_key(g:WindowBufManager, tabpagenr())
    let  g:WindowBufManager[tabpagenr()] = []
  endif
endfunction

function! StoreBufTab()
  call InitTabBufferList()
  " add the new buffer to our explorer
  if index(g:WindowBufManager[tabpagenr()], bufname("%")) == -1 && bufname("%") != ""
    call add (g:WindowBufManager[tabpagenr()], bufname("%"))
  endif
endfunction

function! WindowBufManagerNext()
  call InitTabBufferList()
  " find the next index of the buffer
  let s = index(g:WindowBufManager[tabpagenr()], bufname("%"))
  if (s != -1)
    let s = (s + 1) % len(g:WindowBufManager[tabpagenr()])
    execute 'b ' . get(g:WindowBufManager[tabpagenr()], s)
  endif
endfunction

function! WindowBufManagerPrevious()
  call InitTabBufferList()
  " find the previous index of the buffer
  let s = index(g:WindowBufManager[tabpagenr()], bufname("%"))
  if (s != -1)
    if (s == 0)
      let s = len(g:WindowBufManager[tabpagenr()]) - 1
    else
      let s = s - 1
    endif
    execute 'b ' . get(g:WindowBufManager[tabpagenr()], s)
  endif
endfunction

function! WindowBufManagerCloseTab()
  call InitTabBufferList()

  let bname = bufname("%")
  let s = index(g:WindowBufManager[tabpagenr()], bname)

  if (s != -1)

    let total = len(g:WindowBufManager[tabpagenr()])

    " if we don't switch to another buffer prior to unloading the buffer,
    " it'll close the tab
    if (s > 0)
      execute 'b ' . bufname(get(g:WindowBufManager[tabpagenr()], s - 1))
    elseif (s < total)
      execute 'b ' . bufname(get(g:WindowBufManager[tabpagenr()], s + 1))
    endif

    call remove (g:WindowBufManager[tabpagenr()], bname)

    execute 'bd ' . bname
  else
    execute 'tabclose'
  endif
endfunction

augroup WindowBufManagerGroup
  autocmd! BufEnter * call StoreBufTab()
augroup END

nnoremap <C-r> :call WindowBufManagerPrevious()<CR>
nnoremap <C-e> :call WindowBufManagerNext()<CR>
nnoremap td :call WindowBufManagerCloseTab()<CR>