Slashdot Story: Using MAC Address to Uniquely Identify Computers
GameArena now requires COGS. GameArena has finally, after intensive testing, made COGS a requirement to play on GameArena servers. All servers on GameArena will require you to download and log into the new GameArena client before you will even be able to see them. What is COGS? COGS is MAC address uploader. It gets your MAC address then uploads it so if you do any bad things (i.e. warez, bad account), it can ban you. I see this as an easy fix. COGS is probably easy to fake. I haven't tried it yet. Lastly ethernet MACS can be changed in some instances. Read more here