rel-jump.vim turns [count]j and [count]k motions into jumps. This way
you'll be able to jump back to the previous line by using <C-o>, which is
very handy in conjunction with Vim's relativenumber option.
See :help rel-jump for details.
Install rel-jump.vim by copying the contents of doc and plugin to the
equivalent directories in your .vim directory, or use tpope's pathogen.vim
to keep your .vim directory clean.