Christoffer Niska is a web developer from Helsinki, Finland. He maintains many open source projects that are mainly extensions of the Yii PHP framework. Christoffer's most notable open source effort is Yiistrap, which is an extension for Yii that allows developers to use Twitter Bootstrap along with Yii in a very convenient way.
Christoffer's Twitter handle is @Crisu83 and his online portfolio can be found at http://crisu83.me. Extending Bootstrap is his first official attempt at writing and very likely, not the last.