highlighting redundant whitespace in vim

If you're using vim as your text editor, try adding the following to your .vimrc:

highlight RedundantWhitespace ctermbg=red guibg=red
match RedundantWhitespace /\s\+$\| \+\ze\t/

Handy for telling you when there's invalid whitespace in your code. Telling you with large, red blocks:

See also: this vim tip.