Add this[1] to .vimrc for easy navigation between multiple files in each tab:

    map <C-J> <C-W>j<C-W>_
    map <C-K> <C-W>k<C-W>_
    set wmh=0

Load a new file with the split command:

    :sp <file>

and use Ctrl+j or Ctrl+k to switch between the splits. It's a handy way to organize and edit multiple files.

[1] http://vim.wikia.com/wiki/Switch_between_Vim_window_splits_e...