Signed, is the concept of a website which focuses on helping 2D (and 3D artists to an extent) to improve themselves. It will appeal to artists through fun customization, plenty of artistic challenges through paid commissions with either real money or virtual currency on the site itself, and community moderation due to the underlying system and how the user is rewarded points.

You can download the concept in .psd-format here and get a run-down on how it works by playing the animation in Photoshop.