Games

Birthright Community Home Page
A role-playing game set in the Buffyverse with limited canon character interaction.
http://free-form.greatestjournal.com/

Buffy Quiz Central
Devoted entirely to Buffy all-javascript quizzes.
http://www.angelfire.com/bc/buffyquiz/

Getting Medieval
Role-playing game based on the games by Eden Studio. Also has a large collection of information for both shows, and a character generator.
http://www.geocities.com/exdemon_productions/

The Hellmouth Alliance RPG
Roleplaying game set in both Sunnydale and Los Angeles, California. Post season 5 BtVS, season 2 Angel, but aspects of later seasons (Slayers-in-Training, the First, and Connor) are incorporated.
http://dreamravendesigns.com/Hellmouth_Alliance/

The Heros of Sunnydale
Online roleplaying.
http://www.freewebs.com/theherosofsunnydale/

Nedster's Buffy the Vampire Slayer Drinking Game
Have you ever been watching Buffy, and thought 'I'm not drunk enough'? Well, here's an answer to your problems.
http://www.members.tripod.com/~Nedster69/buffy.html

Sunnydale Cards
Puts collectors in touch with other collectors - allowing them to trade or sell cards. Has an E-Group email group where you can post details of the items you have to trade and the items you are looking for.
http://www.angelfire.com/goth/spikeyvamp/index.html