You can spend all the time you want trying to make beautiful design, clever solutions with jQuery and CSS. It all works perfect in Firefox, Chrome and Opera. It even validates perfectly as XHTML strict with the W3C validators. And then, there's the time consuming monster called Internet Explorer.
Today, I spend half an hour on a silly little bug I've never seen before. It turns out, Internet Explorer doesn't like empty select tags, which by the way is perfectly legal xhtml.
If you don't add any options, IE will never interpret the closing select tag, and your content will never show. White screen of death.
IE6, IE7, IE8