The Gamers' Keep Calendar of Events - Home of the Concentric webring (gamecon). A well-maintained list, although there are quite a few non-gaming conventions in there, or conventions where gaming is a minor part of what's on offer.
Rocky Mountain Benefit Gamers Association - Raises money for small, local charities in the Rocky Mountain region, typically by holding various events throughout the year, many of which are gaming (like board games and role-playing games, not gambling) related.
RPG Registry - Huge database of role-playing Conventions, players, and games - both online and offline.
RPGA Convention Calendar - Webpage goes to current month of official RPGA activities in the United States.
