Here is a good solid list of addons/plugins which are available for WHM. This is by no means a complete list as there are many others out there which are paid addons which will increase functionality.
A-AST RKHUNTER Interface – http://scriptmantra.info/2009/01/the-rkhunter-whm-interface/
A-AST Sendmail Logger – http://scriptmantra.info/2008/07/sendmail-logger/
cPanel WHM APF Interface – http://scriptmantra.info/2009/01/cpanel-whm-apf-interface/
Account DNS Check – http://www.ndchost.com/cpanel-whm/plugins/accountdnscheck/
Add IP to Firewall – http://www.v-nessa.net/2008/06/05/whm-apf-plugin
Clean Backups – http://www.ndchost.com/cpanel-whm/plugins/cleanbackups/
WatchMySQL – http://www.ndchost.com/cpanel-whm/plugins/watchmysql/
ConfigServer Explorer – http://configserver.com/cp/cse.html
ConfigServer Mail Manage – http://configserver.com/cp/cmm.html
ConfigServer Mail Queues – http://configserver.com/cp/cmq.html
ConfigServer ModSec Control – http://configserver.com/cp/cmc.html
ConfigServer Security&Firewall – http://configserver.com/cp/csf.html
ConfigServer Multiple paid offerings – http://configserver.com/ $Fee
Configure cPanel Cron Times – Main>>cPanel>>Manage Plugins
‘cronconfig’ – Check ‘Install and keep updated’
Fantastico De Luxe WHM Admin – https://netenberg.com/fantastico.php – $Fee
Munin Service Monitor – Main>>cPanel>>Manage Plugins
‘munin’ – Check ‘Install and keep updated’
Password Changer – http://www.linux-op.com/password-changer-for-cpanelwhm/
Softaculous – Instant Installs – http://softaculous.com – $Fee
System Log Viewer – LogView – http://logview.org
Nginx Admin – http://nginxcp.com/
WHM Secondary MX Plugin – http://www.ndchost.com/cpanel-whm/plugins/smx/ $Fee
WHMSonic – http://whmsonic.com Manage shoutcast $Fee
WHM LVE Manager Plugin – http://www.cloudlinux.com/docs/whmplugin.php
(if using cloudlinux with WHM/cPanel)
LiteSpeed Plugin – http://www.litespeedtech.com/support/forum/showthread.php?t=2160
(Pre-Release)
WHM RBL Checker – http://www.nickpack.com/article/free-whm-rbl-checker-plugin
(I needed to run
/usr/local/cpanel/scripts/perlinstaller Mail::RBL
/usr/local/cpanel/scripts/perlinstaller Regexp::Common
to get this one to run correctly)
WordPress Versions – http://www.white-hat-web-design.co.uk/blog/whm-plugin-wordpress-versions/
WHMXtra – http://whmxtra.com $Fee
cPremote – http://cpremote.net/ $Fee
Domain Statistics – http://domainsstatistics.gk-root.com (Security Tokens needs to be enabled)
AutoUnblock csf + CSF Manager Auto Unblock http://www.autounblock.com/
Restore manager – http://restoremanager.gk-root.com/
Google Apps Wizard cPanel plugin – http://gaw.gk-root.com/
Enjoy…
