diff --git a/plugins/Blacklist/BlacklistPlugin.php b/plugins/Blacklist/BlacklistPlugin.php
new file mode 100644
index 0000000000..655b0926b7
--- /dev/null
+++ b/plugins/Blacklist/BlacklistPlugin.php
@@ -0,0 +1,203 @@
+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * Plugin to prevent use of nicknames or URLs on a blacklist
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Action
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+    exit(1);
+}
+
+/**
+ * Plugin to prevent use of nicknames or URLs on a blacklist
+ *
+ * @category Plugin
+ * @package  StatusNet
+ * @author   Evan Prodromou <evan@status.net>
+ * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link     http://status.net/
+ */
+
+class BlacklistPlugin extends Plugin
+{
+    public $nicknames = array();
+    public $urls      = array();
+
+    /**
+     * Hook registration to prevent blacklisted homepages or nicknames
+     *
+     * Throws an exception if there's a blacklisted homepage or nickname.
+     *
+     * @param Action $action Action being called (usually register)
+     *
+     * @return boolean hook value
+     */
+
+    function onStartRegistrationTry($action)
+    {
+        $homepage = strtolower($action->trimmed('homepage'));
+
+        if (!empty($homepage)) {
+            if (!$this->_checkUrl($homepage)) {
+                $msg = sprintf(_m("You may not register with homepage '%s'"),
+                               $homepage);
+                throw new ClientException($msg);
+            }
+        }
+
+        $nickname = strtolower($action->trimmed('nickname'));
+
+        if (!empty($nickname)) {
+            if (!$this->_checkNickname($nickname)) {
+                $msg = sprintf(_m("You may not register with nickname '%s'"),
+                               $nickname);
+                throw new ClientException($msg);
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Hook profile update to prevent blacklisted homepages or nicknames
+     *
+     * Throws an exception if there's a blacklisted homepage or nickname.
+     *
+     * @param Action $action Action being called (usually register)
+     *
+     * @return boolean hook value
+     */
+
+    function onStartProfileSaveForm($action)
+    {
+        $homepage = strtolower($action->trimmed('homepage'));
+
+        if (!empty($homepage)) {
+            if (!$this->_checkUrl($homepage)) {
+                $msg = sprintf(_m("You may not use homepage '%s'"),
+                               $homepage);
+                throw new ClientException($msg);
+            }
+        }
+
+        $nickname = strtolower($action->trimmed('nickname'));
+
+        if (!empty($nickname)) {
+            if (!$this->_checkNickname($nickname)) {
+                $msg = sprintf(_m("You may not use nickname '%s'"),
+                               $nickname);
+                throw new ClientException($msg);
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Hook notice save to prevent blacklisted urls
+     *
+     * Throws an exception if there's a blacklisted url in the content.
+     *
+     * @param Notice &$notice Notice being saved
+     *
+     * @return boolean hook value
+     */
+
+    function onStartNoticeSave(&$notice)
+    {
+        common_replace_urls_callback($notice->content,
+                                     array($this, 'checkNoticeUrl'));
+        return true;
+    }
+
+    /**
+     * Helper callback for notice save
+     *
+     * Throws an exception if there's a blacklisted url in the content.
+     *
+     * @param string $url URL in the notice content
+     *
+     * @return boolean hook value
+     */
+
+    function checkNoticeUrl($url)
+    {
+        // It comes in special'd, so we unspecial it
+        // before comparing against patterns
+
+        $url = htmlspecialchars_decode($url);
+
+        if (!$this->_checkUrl($url)) {
+            $msg = sprintf(_m("You may not use url '%s' in notices"),
+                           $url);
+            throw new ClientException($msg);
+        }
+
+        return $url;
+    }
+
+    /**
+     * Helper for checking URLs
+     *
+     * Checks an URL against our patterns for a match.
+     *
+     * @param string $url URL to check
+     *
+     * @return boolean true means it's OK, false means it's bad
+     */
+
+    private function _checkUrl($url)
+    {
+        foreach ($this->urls as $pattern) {
+            if (preg_match("/$pattern/", $url)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Helper for checking nicknames
+     *
+     * Checks a nickname against our patterns for a match.
+     *
+     * @param string $nickname nickname to check
+     *
+     * @return boolean true means it's OK, false means it's bad
+     */
+
+    private function _checkNickname($nickname)
+    {
+        foreach ($this->nicknames as $pattern) {
+            if (preg_match("/$pattern/", $nickname)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}