TeamViewer

Remote Control And Desktop Sharing
TeamViewer is an easy to use solution for remote control, desktop sharing and file transfer that works behind any firewall and NAT proxy.
All you need to do is run TeamViewer on both machines and exchange the automatically assigned ID codes with the remote user, this can be done by email or over the phone.
Once you enter the ID code and password, you can connect to the remote computer and operate it as if you were sitting in front of it.
In addition to remote control, TeamViewer also offers a presentation mode that allows you to broadcast your desktop to the remote computer, as well as file transfers, session recording, VNC compatibility and support for VPN connections.
TeamViewer also provides a free iPhone/Android app that you can use to access your own or other PCs remotely from your phone.Free for non-commercial use.