PuTTY - Popular free terminal application. Mostly used as an SSH client.
TeamViewer - TeamViewer lets you establish a connection to any PC or server within just a few seconds.
SecPanel - SecPanel is an Ssh GUI for Unix.
mRemoteNG - mRemoteNG is a fork of mRemote, an open source, tabbed, multi-protocol, remote connections manager.
Lterm - Lterm is a terminal emulator for GNU/Linux systems.
join.me - Instant screen sharing. Instant Aha!