Put this in one of your theme's stylesheets - it'll change a clunky, large, and unweildy comment form into a more compact and user-friendly form:

/* Comment Form */
#comment-form {
	padding: 1em;
	margin: 1em;
	background: #FFF;
	position: relative;
}
#edit-name-wrapper {
margin-top: 0;
}
#edit-homepage-wrapper {
width: 8em;
top: 0em;
left: 25em;
position: absolute;
}
#edit-homepage-wrapper,
#edit-homepage {
color: #777;
}
#comment-form .form-actions {
margin-bottom: 0;
}
#comment-form input.form-text,
#comment-form textarea,
#comment-form input {
margin: 0;
}