Some Wordpress plugins are often updated, which is good think. Plugins that are updated are 100% compatible with last Wordpress version and they also are the most secure possible. A plugin that has not been updated for a long time might not work with last Wordpress version and might create a security breach for you website.
This plugin adds a security question to the Buddypress registration page.
Exclusive Content Password Protect is a plugin that allows you to hide a section (or multiple sections) of content on your page or post.
wpMyRollPage displays your your links (blogroll and the such) on a page of your choosing, the output can be formatted in various ways.
Adds Nivo Slider to a post/page with no coding. Builds sliders from a post images, featured images in posts, or from NextGen galleries.
A widget which will display latest Flickr photos from specify user, user set, group or public. You also can set size, tags, number and sorting.
A twitter widget for plugin with YQL support, for the people that twitter.com blocked for them.