personal urls

[eluser]decob[/eluser]
looking to add a feature for members of a site where they would have a personal url based on their first name, www.example.com/john which would obviously map to the main controller,

Given that the majority of the site is actually flash with some data being pulled in fron codeigniter, i'd need that controller not to be mapped back to the main controller.

At some stage in the future i may check the entered names against a database to ensure it's an allowable name.., as i'd rather not have people being able to enter any random crap like
www.example.com/isacrapwebsitename

So question is, whats the best approach, routes or some form of mod_rewrite magic