This is a list of plugins which I have released publicly. They both require BuddyPress and a recent version of WordPress.
Welcome Pack
When a user registers on your site, Welcome Pack lets you automatically send them a friend or group invitation, or a welcome message. You can also customise the default emails sent by BuddyPress to ensure that they match the brand and tone of your site.
Achievements
This plugin was inspired by the Achievement system in World of Warcraft and the various user points plugins for systems such as phpBB. Achievements in BuddyPress are self-contained goals which aim to help encourage people to keep using and contributing to your website.