I refactored quite a bit of the user.module:

$ diffstat user.patch
database/database.mysql |    4
database/database.pgsql |    2
database/updates.inc    |   10 -
modules/block.module    |   20 +-
modules/locale.module   |    9
modules/profile.module  |  108 +++++++----
modules/system.module   |    8
modules/user.module     |  456 +++++++++++++++++++-----------------------------
8 files changed, 289 insertions(+), 328 deletions(-)

More functionality, less code.  Here is a list of the changes:

- Some user API changes:
   + When $type is 'form', you have to return an associative array of groups.  In turn, each group is an array with a 'title', 'data' and 'weight'.
   + A new $type has been added, namely 'categories'.  User settings can be organized in categories.  Categories can be sorted, as can the groups within a category.  (Ordering 'categories' is somewhat broken due to a bug in the menu system.)

- The 'my account > edit' page will use subtabs for each 'category'.  Read: you can break down the account settings into multiple subpages.

- Profile module improvements:
   + Added support for private fields to the profile module!
   + Improved workflow of profile administration pages.
   + Improved the form descriptions.

- Code improvements:
   + Unified user_edit() and user_admin_edit().
   + Unified and cleaned up the validation code.  Fixed some validation glitches too.

1 files changed, 12 insertions, 10 deletions

diff --git a/modules/block.module b/modules/block.module
index 455380f12..358654a01 100644
--- a/modules/block.module
+++ b/modules/block.module
@@ -357,20 +357,22 @@ function block_admin() {
  * Allow users to decide which custom blocks to display when they visit
  * the site.
  */
-function block_user($type, $edit, &$user) {
+function block_user($type, $edit, &$user, $category = NULL) {
   switch ($type) {
     case 'form':
-      $result = db_query('SELECT * FROM {blocks} WHERE custom = %d ORDER BY module, delta', 1);
-
-      while ($block = db_fetch_object($result)) {
-        $data = module_invoke($block->module, 'block', 'list');
-        if ($data[$block->delta]['info']) {
-          $form .= form_checkbox($data[$block->delta]['info'], "block][$block->module][$block->delta", 1, isset($user->block[$block->module][$block->delta]) ? $user->block[$block->module][$block->delta] : $block->status);
+      if ($category == 'account') {
+        $result = db_query('SELECT * FROM {blocks} WHERE custom = %d ORDER BY module, delta', 1);
+
+        while ($block = db_fetch_object($result)) {
+          $data = module_invoke($block->module, 'block', 'list');
+          if ($data[$block->delta]['info']) {
+            $form .= form_checkbox($data[$block->delta]['info'], "block][$block->module][$block->delta", 1, isset($user->block[$block->module][$block->delta]) ? $user->block[$block->module][$block->delta] : $block->status);
+          }
         }
-      }
 
-      if (isset($form)) {
-        return array(t('Block configuration') => $form);
+        if (isset($form)) {
+          return array(array('title' => t('Block configuration'), 'data' => $form, 'weight' => 2));
+        }
       }
 
       break;