Chess symbols in Unicode:
♔ - ♔
♕ - ♕
♖ - ♖
♗ - ♗
♘ - ♘
♙ - ♙
♚ - ♚
♛ - ♛
♜ - ♜
♝ - ♝
♞ - ♞
♟ - ♟
By now, you will have noticed, O astute reader, that these all come on simple, white backgrounds. Apparently, the good people defining the Unicode standard don't play chess enough to understand how clueless this is.
Bottom line: if you want to node a chessboard with black squares, you're in trouble. Still, I'm sure you're creative enough to find a workaround.
If your browser doesn't display the characters, you'll need to get yourself a font that contains the upper range of Unicode characters - say, Arial Unicode MS, or some such.