Here's what I need, I'm trying to make short urls available for users on my domain. For example: domain.com/user. Yes, this is a necessary function of my site, not just for convenience. The problem is I also have directories in my root directory that could mimic these usernames without being related at all (for example, /css or /images), see how those could both be usernames? How can I avoid this problem?
Indeed, I meant to mention that you would have to either pre-register certain nicknames, or have a black list that isn't usable. Alternatively you could use a different subdomain allowing full usage of all paths.