These look the same as their real counterparts in Safari, Chrome, and Firefox. They degrade gracefully and look OK in Opera and IE9, too.
Demo: http://jsfiddle.net/ThinkingStiff/AbKTQ/
CSS:
textarea {
    height: 28px;
    width: 400px;
}
#textarea {
    -moz-appearance: textfield-multiline;
    -webkit-appearance: textarea;
    border: 1px solid gray;
    font: medium -moz-fixed;
    font: -webkit-small-control;
    height: 28px;
    overflow: auto;
    padding: 2px;
    resize: both;
    width: 400px;
}
input {
    margin-top: 5px;
    width: 400px;
}
#input {
    -moz-appearance: textfield;
    -webkit-appearance: textfield;
    background-color: white;
    background-color: -moz-field;
    border: 1px solid darkgray;
    box-shadow: 1px 1px 1px 0 lightgray inset;  
    font: -moz-field;
    font: -webkit-small-control;
    margin-top: 5px;
    padding: 2px 3px;
    width: 398px;    
}
HTML:
<textarea>I am a textarea</textarea>
<div id="textarea" contenteditable>I look like textarea</div>
<input value="I am an input" />
<div id="input" contenteditable>I look like an input</div>
Output:
