Index: wp-admin/includes/class-wp-posts-list-table.php
===================================================================
--- wp-admin/includes/class-wp-posts-list-table.php	(revision 21256)
+++ wp-admin/includes/class-wp-posts-list-table.php	(working copy)
@@ -492,7 +492,10 @@
 
 			case 'cb':
 			?>
-			<th scope="row" class="check-column"><?php if ( $can_edit_post ) { ?><input type="checkbox" name="post[]" value="<?php the_ID(); ?>" /><?php } ?></th>
+			<th scope="row" class="check-column"><?php if ( $can_edit_post ) { ?>
+			<label class="screen-reader-text" for="cb-select-<?php the_ID(); ?>"><?php printf( __( 'Select %s' ), $title );
+			?></label><input id="cb-select-<?php the_ID(); ?>" type="checkbox" name="post[]" value="<?php the_ID(); ?>" />
+			<?php } ?></th>
 			<?php
 			break;
 
Index: wp-admin/includes/class-wp-terms-list-table.php
===================================================================
--- wp-admin/includes/class-wp-terms-list-table.php	(revision 21256)
+++ wp-admin/includes/class-wp-terms-list-table.php	(working copy)
@@ -236,9 +236,10 @@
 		$default_term = get_option( 'default_' . $taxonomy );
 
 		if ( current_user_can( $tax->cap->delete_terms ) && $tag->term_id != $default_term )
-			return '<input type="checkbox" name="delete_tags[]" value="' . $tag->term_id . '" />';
-		else
-			return '&nbsp;';
+			return '<label for="cb-select-' . $tag->term_id . '" class="screen-reader-text">' . sprintf( __( 'Select %s' ), $tag->name )
+				. '</label><input type="checkbox" name="delete_tags[]" value="' . $tag->term_id . '" id="cb-select-' . $tag->term_id . '" />';
+
+		return '&nbsp;';
 	}
 
 	function column_name( $tag ) {
Index: wp-admin/includes/class-wp-list-table.php
===================================================================
--- wp-admin/includes/class-wp-list-table.php	(revision 21256)
+++ wp-admin/includes/class-wp-list-table.php	(working copy)
@@ -664,6 +664,13 @@
 		else
 			$current_order = 'asc';
 
+		if ( ! empty( $columns['cb'] ) ) {
+			static $cb_counter = 1;
+			$columns['cb'] = '<label class="screen-reader-text" for="cb-select-all-' . $cb_counter . '">' . __( 'Select All' )
+				. '</label><input id="cb-select-all-' . $cb_counter . '" type="checkbox" />';
+			$cb_counter++;
+		}
+
 		foreach ( $columns as $column_key => $column_display_name ) {
 			$class = array( 'manage-column', "column-$column_key" );
 
Index: wp-admin/includes/class-wp-comments-list-table.php
===================================================================
--- wp-admin/includes/class-wp-comments-list-table.php	(revision 21256)
+++ wp-admin/includes/class-wp-comments-list-table.php	(working copy)
@@ -317,8 +317,10 @@
 	}
 
 	function column_cb( $comment ) {
-		if ( $this->user_can )
-			echo "<input type='checkbox' name='delete_comments[]' value='$comment->comment_ID' />";
+		if ( $this->user_can ) {
+			echo '<label class="screen-reader-text" for="cb-select-' . $comment->comment_ID . '">' . __( 'Select comment' )
+				. "</label><input id='cb-select-$comment->comment_ID' type='checkbox' name='delete_comments[]' value='$comment->comment_ID' />";
+		}
 	}
 
 	function column_comment( $comment ) {