Put icon inside input element in a form

The CSS solutions posted by others are the best way to accomplish this.

If that should give you any problems (read IE6), you can also use a borderless input inside of a div.

<div style="border: 1px solid #DDD;">
    <img src="icon.png"/>
    <input style="border: none;"/>
</div>

Not as "clean", but should work on older browsers.

The site you linked uses a combination of CSS tricks to pull this off. First, it uses a background-image for the <input> element. Then, in order to push the cursor over, it uses padding-left.

In other words, they have these two CSS rules:

background: url(images/comment-author.gif) no-repeat scroll 7px 7px;
padding-left:30px;