I'd like to see more kinds of art, much like the current slabs we have--which I hope will eventually be able to be carved with things other than a memorial. These items would serve no particular purpose other than allowing the expression of art, but some could be placed to produce good thoughts, like slabs or statues. Their use could be culture-dependent; e.g. not allowing elves to make paintings. Mosaics and paintings should probably get their own skill, embroidery can use "clothier".
Mosaics: An image made from blocks of metal, glass and stone or gems. It is always constructed on a floor of wall and acts like an engraving, allowing you to decorate constructed walls and floors. Each mosaic can incorporate multiple (three? four?) materials, but the item types can't be mixed. (To prevent aesthetic choices that are too terrible.)
Embroidery: A craft made from cloth, which can then be decorated with dyed thread. Like any cloth image decorating an item, but for its own sake. Can contain writing or imagery.
Painting: A wood crafter can create a panel. A clothier can process a panel with cloth to make a canvas. Painters can make images on panels and canvases with dye, being able to incorporate multiple dyes. Placeable as furniture. (Not sure how you could make one hang on a wall.)
No more will our fortresses have to make tools, food or other useful things! We can build a true Bohemian fortress that subsists on the profit from selling embroideries of dwarven proverbs and paintings of the Attempted Theft of Knotsmelters in the Summer of 869.