Started in 2004, so contains some outdated stuff for sure.
.htaccessa[href]:hover:active be used?@page rulebackground-attachment and scrolling speedrgba() and a hack for IEbackground-position have a funny way of calculating:before & :afterinput with only a border on the bottom could be handy for printable formsborder can have four different border-colorsclear behavior in Geckotable version for comparison)> selector in Internet Explorerclear: both;margins.or.multi-class.selectors)direction and unicode-bidi to swap wordsdisplay: inline-block; doesn't work too great cross browser:first-letter & inline|block:first-letter & the selector subjectfont propertiestext-transform: lowercase; and font-variant: small-caps; is buggy in IEcolor, sort of :)form layouts:hover:after { content: '\A bar'; } seems to crash Safari 1.3 and 2:hover in Internet Explorera:hover * { visibility: visible; } has a bug in Internet Explorer 6!important rule<li>'s inline, without extra spaceline-height thingylinks to stylesheets a title?min-height in Internet Explorer<span>Semantics</span>, <span>why</span>?outline property, looks like borderoverflow: auto;position: fixed; in Internet Explorer::selection selector and some applicable propertieslegend elementmeter elementempty-cells property and some JavaScript for Internet Explorertable-layout property, using fixed and widthtext-decoration: underline; for some anchorstext-overflow to create nice effects…text-shadow and an alternative method.highlight:after { content: url('javascript:window.focus();'); } for Opera Chat?text-decoration and color togethervertical-align & line-height to vertically center a piece of textbuttons in Explorer?word-wrap: break-word;z-index examplez-index example, which provides problems with the stacking contextabbr and/or acronym?<abbr> for Internet Explorerselect box doesn't have an accesskey<button> as submit buttons<!-- Some comments are weird science in Gecko --><!--[if lt IE 6]>Conditional comments to target IE<![endif]--><!--[if !IE]><!-->Conditional comments to target anything but IE<!--<![endif]-->utf-8?<STRONG>case</strong> of tags change the <em>filesize</EM>?id="tags" is considered harmful!<input type="image"> is pretty useless sometimes<isindex>?<a name="foo"> to jump to a section, but id'salt attribute?<meta name="description"> indexed?http-equiv and a real HTTP header<meta name="keywords"> indexed?<object> to display an image and provide alternative marked up content#fragment #identifier in Opera, when using Apache MultiViews<select multiple[="multiple"]> or a list with <input type="checkbox">s?­ and how do search engines index it?iframe elements again?<b> & <i> aren't deprecated, <u> istarget attribute in a strict DOCTYPE<thead> and <tfoot> rendered when printed?<canvas> test<datalist><!DOCTYPE HTML>) and the rendering mode it triggerstype attribute for input elementselement.getAttribute('attr') and element.attrif (object) and if (object())onchange or onclick?.innerHTMLdefer do?document.compatMode to get the page rendering modeonselectionchange event and the clipboardData objectinclude() construct/function work in JavaScriptinput and use window.opener to fill the controlJSONRequest() become available?div scroll simultaneouslymatchMedia<script type="text/foobarscript">JavaScript and its MIME type(s)</script>number_format() in JavaScripteval()onload event isn't triggered if the page loading is canceledonmouseover eventpreviousSibling meets whitespacescrollIntoView()?!select box with some fluffy optionsonchange event of a select boxalign="char"defaultValue property of an input with onfocus and onblurtext-shadow in CSS doesn't work too well, this doesn't either :)classesXMLHttpRequest to check links on page loadXMLHttpRequest to fetch next and previous items (known to some as AJAX)get_headers()text/plain and text/html mails, using multipart/alternativehtmlspecialchars() thingyutf-8