How do sites prevent vanity URLs from colliding with future features ?
My answer to How do sites prevent vanity URLs from colliding with future features ? on QuoraLanyrd.com uses Twitter screen names for profile URLs, which means this trick doesn’t work—I don’t have any control over what Twitter allows people to register. As a result, our profile pages are http://lanyrd.com/people/simonw/—but we do redirect http://lanyrd.com/simonw as a shortcut, assuming it doesn’t collide with a URL already used by the site. We’re not really promoting that feature though as we don’t want people to link to it when we can’t guarantee that it will always work for their account (if you have a username that’s unlikely to clash with a site feature you should be fine though).