Harold Cohen is probably the most famous example--- a painter who also programs AI systems (which are themselves painters...): http://crca.ucsd.edu/~hcohen/

Although, looking for painters who are also programmers, but programmers of things other than computer-art systems is also an interesting question. Likewise with musicians, people who are musician-programmers in computer music, and people who are musicians and also programmers separately, might be interesting to consider as different groups.