TeamViewer is a beginner-friendly, feature-rich remote desktop management tool that boasts exceptional security features, an intuitive user interface, and a great selection of extra screen sharing and conferencing tools.
Empathy - Apps/Empathy - GNOME Wiki!
AnyDesk - AnyDesk is the world's most comfortable remote desktop application. Access all your programs, documents and files from anywhere, without having to entrust your data to a cloud service.
Adium - Adium is a free instant messaging application for Mac OS X that can connect to AIM, MSN, Jabber, Yahoo, and more.
LogMeIn - LogMeIn gives you fast, easy remote access to your PC or Mac from your browser, desktop and mobile...
IM+ - Chat everywhere! IM+ is the most widely used mobile IM app! Connect all-in-one to MSN, Yahoo!, Goo...
join.me - Instant screen sharing. Instant Aha!