Switch to last-active tab in VIM

Put this in your .vimrc:

if !exists('g:lasttab')
  let g:lasttab = 1
endif
nmap <Leader>tl :exe "tabn ".g:lasttab<CR>
au TabLeave * let g:lasttab = tabpagenr()

Then, in normal mode, type \tl to swap to the tab you viewed last.