What spells can you cast with a magic marker?

I can seduce the minds of the unwashed masses with the spell of a magic marker on a sign held aloft, or capture the heart of a kindergarten child with the smooth streams of a rainbow upon a plain bleached poster. The spells cast by magic markers are great and small, few, far between and sparse, voluminous and far reaching, while never expanding into the world of impossibility; if it can be written with a magic marker, can it really be that hard to do?