The Contributor rank is a user group specifically for members of the community that contribute quality hacks on a regular basis. This rank is not used to signify a member of the community that contributes to discussions and assists users. Typically, users who help out and actively assist their section apply for Minion.
Contributors are typically suggested by users who have access to the Memeber Level 2 section, or even staff members. This rank is removed if you cease to contribute hacks, so it is not permanent once you have it.