I like my theme to have edit buttons, because it makes life easier for the WordPress end user. When I’m logged on and I navigate to the C# section, I see the following:

Edit category

Creating an edit button is not that hard, just use the following snippet in the archive.php of your theme:

<?php if(current_user_can( 'manage_options' )) {
    $term = get_queried_object();
        if(is_tag()){ ?>
            <a class="edit-link" 
               href="/wp-admin/edit-tags.php?action=edit&taxonomy=post_tag&tag_ID=<?php echo $term->term_id; ?>">Edit tag</a>
        <?php } else if(is_category()){ ?>
            <a class="edit-link" 
               href="/wp-admin/edit-tags.php?action=edit&taxonomy=category&tag_ID=<?php echo $term->term_id; ?>">Edit category</a>
        <?php } 
} ?>

The links can be styled in your style.css. My theme uses the following styling:

.edit-link { 
	float: right; 
	display: block; 
	border: 2px solid #ddd; 
	padding: 2px 14px; 
	color: #aaa; 
	font-size: 0.85em; 
	text-transform: uppercase; 
	letter-spacing: 1px; 
	font-weight: bold; 
	font-family: 'Source Sans Pro', Helvetica, Arial; 

.edit-link:hover { 
	color: #000; 
	border-color: #000; 
	text-decoration: none; 

So, that’s it. One step closer to a high-usability-theme!