Direct Connection 
- Remote Desktop Connection

• RDP Protocol
• Formerly Terminal Services Client. Clients available on many platforms.

- VNC (Virtual Network Computing)

• RFB (Remote Frame Buffer) Protocol
• GPL’ed, Client & Server available for numerous platforms.
• Slower than RDP but allows user interaction.
• TightVNC, RealVNC, UltraVNC
• TightVNC is ARD (Apple Remote Desktop) compatible.

Proxied Connections
 
- LogMeIn

• Windows, Mac

 


- GoToMyPC (Citrix)

• Windows, Mac

 
- Teamviewer

• Windows, Mac, Linux, Android, iPhone
• Free version does not require any registration or setup.

All have free versions available for personal use.
Allows passive remote control, no proactive monitoring