Index: wp-admin/admin-functions.php
===================================================================
--- wp-admin/admin-functions.php	(revision 3053)
+++ wp-admin/admin-functions.php	(working copy)
@@ -763,12 +763,13 @@
 
 function meta_form() {
 	global $wpdb;
+	$limit = apply_filters('meta_form_limit', 50);
 	$keys = $wpdb->get_col("
 			SELECT meta_key
 			FROM $wpdb->postmeta
 			GROUP BY meta_key
 			ORDER BY meta_id DESC
-			LIMIT 10");
+			LIMIT $limit");
 ?>
 <h3><?php _e('Add a new custom field:') ?></h3>
 <table cellspacing="3" cellpadding="3">
@@ -1733,4 +1734,4 @@
 		return array((int) ($width / $height * $hmax), $hmax);
 }
 
-?>
\ No newline at end of file
+?>