Echo logged-in user’s site URL

Heya,

I have a comment form for logged in users that basically looks the same as the one shown to regular visitors, but has the fields disabled and thus basically there for cosmetic reasons.

The code I have is:

<div class="your_name">
	<label for="author">Logged In As:</label>
	<input class="text" id="author" name="author" type="text" disabled="disabled" value="<?php echo $user_identity; ?>" tabindex="1" />
</div>
<div class="website">
	<label for="url">Website:</label>
	<input class="text" id="url" name="url" type="text" disabled="disabled" value="<?php echo $user_url; ?>" tabindex="2" />
</div>

This is essentially fine, but the variable I’m using to try and echo the user’s profile URL does nothing. Does anyone know what the correct variable to use here would be?