Someone earlier in this thread asked what outside-the-box things people are doing with their tables.
Just for "fun" to demonstrate how one can begin creating some very complex tables, I did a 19x25 table using four different 16x16 px squares...just three different shades (black, dark grey, light grey) and a white square.
Using
BB Table Maker 2.2.xls, I was able to create this image. I can't imaging trying to do this manually.