I found this cool article about CSS tricks. I am just showing some of them.
Rounded corners without images
<div id=”container”>
<b class=”rtop”>
<b class=”r1″></b> <b class=”r2″></b> <b class=”r3″></b> <b class=”r4″></b>
</b>
<!–content goes here –>
<b class=”rbottom”>
<b class=”r4″></b> <b class=”r3″></b> <b class=”r2″></b> <b class=”r1″></b>
</b>
</div>
.rtop, .rbottom{display:block}
.rtop *, .rbottom *{display: block; height: 1px; overflow: hidden}
.r1{margin: 0 5px}
.r2{margin: 0 3px}
.r3{margin: 0 2px}
.r4{margin: 0 1px; height: 2px}
Double blockquote
blockquote:first-letter {
background: url(images/open-quote.gif) no-repeat left top;
padding-left: 18px;
font: italic 1.4em Georgia, “Times New Roman”, Times, serif;
}
Find more tips @ StylizedWeb.com
ModalBox is a JavaScript technique for creating modern (Web 2.0-style) modal dialogs or even wizards (sequences of dialogs) without using conventional popups and page reloads. It’s inspired by Mac OS X modal dialogs. And yes, it may also be useful for showing larger versions of images.

ModalBox is built with pure JavaScript and is based on Sam Stephenson’s excellent Prototype JavaScript Framework, script.aculo.us and valid XHTML/CSS. ModalBox uses AJAX to load content.
more @ wildBit.com
Over the last few years, all of the major browsers have included support for a special set of 140 colors that are recognized by their color name within HTML or CSS code.
This means that rather than having to remember that the color orange is specified with the hex code “#FFA500″, you can simply type the word “orange” when specifying a color in your code and the browser will automatically translate it to its hex code.
Below link is a handy reference list of all 140 browser-supported named colors, which you can quickly sort by color family or name.
Color Schemer