If you're nostalgic about overcoming Y2K and playing Final Fantasy XI in its early days, a private, free FFXI server is recruiting new members. From the site:
"This server is specifically setup for 2003-2004. Enjoy the true old school feeling of when FFXI was first released!
The server is permanent and replicated on 3 other servers. Going down, disappearing, offline is NOT an option with us - unlike other servers that randomly shut off.
You will NOT lose your character data or information, ever. We back your character data up daily and send you the SQL file. Therefor, you have the option to move your current character data to another server, if you choose!"
The claim is that you don't need to buy anything, or even own CD keys to play. You can find more information and setup steps over at http://www.ffxiservercontrol.com/ .
Thumbstick Athletes has not attempted to join, so let us know in the comments if you've had success.