Jitsi (formerly SIP Communicator) is an audio/video and chat communicator that supports protocols such as SIP, XMPP/Jabber, AIM/ICQ, Windows Live, Yahoo!, Bonjour, and many other useful features. It is currently the most feature rich Internet Communicator, and is the only one to provide encrypted audio/video calls, desktop streaming and sharing, and chat on Windows, Mac OS X, and Linux with both the SIP and XMPP protocols.
FF Multi Converter is a simple graphical application that converts audio, video, image, and document files between all popular formats, using and combining other programs. It uses ffmpeg for audio/video files, unoconv for document files, and the ImageMagick library for image file conversions.
Unsettings is a graphical configuration program for the Unity desktop environment which lets you change some of Unity's settings. It also lets you save your settings into and load from a text file (in JSON format) so you can easily back up your settings or copy them to a different account.