I’m not sure if this is the solution guys, but I was getting annoyed with having to insert images, and each time change them to full size, then having to change the link URL to none.
I found the solution in another thread on here for the image size default, but for the link to be blank by default (for individual images), I just need to change some code in my wp-admin/includes/media.php file starting line 263 (in wordpress 2.6)
'url' => array(
'label' => __('Link URL'),
'input' => 'html',
'html' => "
<input type='text' name='attachments[$post->ID][url]' value='" . __('') . "' /><br />
<button type='button' class='button url-$post->ID' value=''>" . __('None') . "</button>
<button type='button' class='button url-$post->ID' value='" . attribute_escape($file) . "'>" . __('File URL') . "</button>
<button type='button' class='button url-$post->ID' value='" . attribute_escape($link) . "'>" . __('Post URL') . "</button>
<script type='text/javascript'>
jQuery('button.url-$post->ID').bind('click', function(){jQuery(this).siblings('input').val(this.value);});
</script>\n",
'helps' => __('Enter a link URL or click above for presets.'),
If you don’t read code easily like me, all I did was remove a bit of text in the input type line to leave it looking like what I’ve posted above.