Another really, really useful bit of code that I have been using is in CSS. CSS have default values, and often programmers will list all of the page elements to clear these values right at the beginning of the stylesheet, like so:
html, body, h1, h2, h3, h4, h5, h6, p, ul, ol, dl, li, dd, dt, img,
blockquote, q, table, thead, tbody, tfoot, caption, th, tr, td,
a, form, input, textarea, pre {margin: 0; padding: 0;}
However, by using * as a wildcard, like you can in many languages, you can do all of that with a much smaller block of code:
* {margin: 0; padding: 0;}
As of yet I haven’t found any browser issues with this.