Jitsi is a F/OSS multiprotocol text chat/voice over IP/video chat application. It supports a large number of instant messaging and VoIP protocols, not only for IM but as transport and control channels for VoIP and video conferencing. If there's a way to get your streams through it'll do it. Natively supports OTR for protecting chats. Implements SRTP and ZRTP for encrypted conferencing. Supports DNSSEC. Aims to replace Skype as a more secure, open source package.