Number of forum users with a given domain in their email address.

mysql> SELECT SUBSTR(email, INSTR(email, '@')+1) AS domain, COUNT(*) as count FROM user GROUP BY domain ORDER BY count DESC LIMIT 30;
+------------------+-------+
| domain           | count |
+------------------+-------+
| hotmail.com      |  7322 |
| yahoo.com        |  3087 |
| gmail.com        |  1660 |
| aol.com          |   658 |
| msn.com          |   614 |
| gmx.de           |   402 |
| web.de           |   372 |
| comcast.net      |   352 |
| yahoo.co.uk      |   352 |
| gmx.net          |   239 |
| yahoo.fr         |   218 |
| ntlworld.com     |   212 |
| wanadoo.fr       |   201 |
| sbcglobal.net    |   184 |
| free.fr          |   182 |
| yahoo.com.br     |   153 |
| blueyonder.co.uk |   141 |
| yahoo.de         |   133 |
| btinternet.com   |   129 |
| libero.it        |   117 |
| yahoo.ca         |   107 |
| earthlink.net    |   101 |
| cox.net          |   100 |
| hotmail.co.uk    |    92 |
| tiscali.co.uk    |    90 |
| t-online.de      |    84 |
| freenet.de       |    82 |
| netscape.net     |    79 |
| hotmail.fr       |    77 |
| sympatico.ca     |    75 |
+------------------+-------+
30 rows in set (0.25 sec)