Yet another installment of Aaron makes you a table.  This time I present you with local_user_info, a table that contains a record for every user in every Wikimedia project wiki along with their centralauth globaluser ID if applicable.  Unlike the centralauth tables, this table contains a user's local user_id -- a persistent identifier for that user that persists between renames.  

Notably, this table can be used along with editor_month (from my last have-a-table email) to track user activity more easily cross-wiki.  

mysql:research@analytics-store.eqiad.wmnet [staging]> select * from local_user_info limit 3;
+--------+---------+-------------------+---------------+----------------+-----------------+
| wiki   | user_id | user_registration | globaluser_id | user_attached  | attached_method |
+--------+---------+-------------------+---------------+----------------+-----------------+
| bgwiki |       1 | NULL              |           488 | 20080325163146 | password        |
| bgwiki |       2 | NULL              |             0 | NULL           |                 |
| bgwiki |       3 | NULL              |         30314 | 20080805113516 | primary         |
+--------+---------+-------------------+---------------+----------------+-----------------+
3 rows in set (0.00 sec)

mysql:research@analytics-store.eqiad.wmnet [staging]> explain local_user_info;
+-------------------+-----------------------------------------------------------------+------+-----+---------+-------+
| Field             | Type                                                            | Null | Key | Default | Extra |
+-------------------+-----------------------------------------------------------------+------+-----+---------+-------+
| wiki              | varbinary(50)                                                   | YES  | MUL | NULL    |       |
| user_id           | int(11)                                                         | YES  |     | NULL    |       |
| user_registration | varbinary(14)                                                   | YES  |     | NULL    |       |
| globaluser_id     | int(11)                                                         | YES  | MUL | NULL    |       |
| user_attached     | varbinary(14)                                                   | YES  |     | NULL    |       |
| attached_method   | enum('primary','empty','mail','password','admin','new','login') | YES  |     | NULL    |       |
+-------------------+-----------------------------------------------------------------+------+-----+---------+-------+
6 rows in set (0.01 sec)

Have fun!
-Aaron