This is a version of Wombat (vimscript #1778) by Lars Nielsen that also works on xterms with 256 colors. A customized version is also available, with additional highlighting groups for diff mode and search. Put the script into your Vim 'colors' directory (e.g. ~/.vim/colors), and load it with the command :colorscheme wombat256 or :colorscheme wombat256mod