Email Users allows you to send an e-mail to your registered blog users, based on their role.
iCal Posts creates an iCal feed from your blog posts, which can be added to pretty much any popular website (such as Google Calendar) or application (such as Microsoft Outlook).
IIS Authentication allows WordPress to recognize IIS authentication methods, allowing the user to log in with an IIS authentication method such as Windows Authentication, Basic Authentication, or the ASP.NET forms authentication.
WP-PTViewer includes interactive panoramas inside posts and pages.
Short Permalink includes short permalinks on each post to use in microblogging, emails, IM or another notes.
Shutter Reloaded is an image viewer for your website that works similarly to Lightbox, Thickbox, etc. but is lean and mean at only 8KB size. It does not require any external libraries.
Twitter for WordPress displays yours latest tweets in your WordPress blog.