If you have any pixel structures that don't fit in GEM, there is GridFlow.
Supports up to 15 dimensions (though there's hardly ever a need for more than 5).
A comedy cartoon I done that has a mention of 5 dimensions. http://www.youtube.com/watch?v=xZUTn-rie8w
i like it! when Matju mentioned 15 dimensions, this one came to my mind: http://www.youtube.com/watch?v=8Q_GQqUg6Ts
Andras