Now you can easily create unique feed URLs for each registered user in your WordPress site simply by adding Feed Keys to the end of the existing feed URL. Unique Feed Keys are made by hashing username or email against a randomly generated key. You can choose the key length and algorithm to use to hash the salt and the key together using new WordPress plugin called Private Feed Key. It adds adds a 32bit (or 40bit) key for your website users and creates a unique feed URL.
You can moderate new BuddyPress members, fight spams, set BuddyPress groups and sites and allows new members to join them from the registration page by using BuddyPress Registration Options plugin.
Generally WordPress website owners use CAPTCHA plugins for protecting their site from Spam Bots. This tutorial explains you working of a free WordPress plugin you can use for protecting your WordPress installation from Spam Bots without installing any type of captcha plugin. Keypic.Com is an online service that provides you with free plugins now only for WordPress but for other Opensource blogging platforms like Drupal and next month (as scheduled) they would be launching plugins for Joomla, php. More plugins would be available in the near future for MediaWiki, Typo3, vBulletin. For more information on plugins visit here.
Easily apply comment moderation blacklist on registration and prevent spammers for registering on your WordPress site.