MarkShift is a project mainly written in Vim Script, it's free.
Highlights indents when "expandtab" option is on.
This is a mirror of http://www.vim.org/scripts/script.php?script_id=627
Usefull for editing indented source files which have been edited with the expand tab setting. When activated the first space out of every N spaces is highlighted. N is worked out automaticlly from the shiftwidth setting of the buffer.