Many sites have posted about the Expo, but it would be great to improve coverage from news sites and from the QuakeWorld side. (Anyone active on quakeworld.nu?) Also valuable are comments on popular game sites if you can work a Quake Expo mention in there...
Twitter posts are a top referrer. Use #qexpo
Sites currently referring to the Quake Expo site via links in news, blogs, or forum posts include:
celephais.net (func_msgboard)
Twitter
quake3world.com
team102.ru
disqus.com (mostly via PC Gamer site)
forums.insideqc.com
quakeone.com
forums.somethingawful.com
forums.xonotic.org
insideqc.com
Reddit
earthquake.fuzzylogicinc.com
forum.tastyspleen.net
forums.unvanquished.net
quaddicted.com
freegamer.blogspot.com
gamingonlinux.com
quakehaus.com
freegamer.blogspot.de
moddb.com