If you use Chrome for browsing, there is a new extension called Bigger Golem. It has two Japanese shogi sets to choose from as an option from the default international set.
I have suggested some small improvements for Twixt and Hex, which might show up soon. If there are other improvements you would like to see, you could email the developer.
Trevor Cook has contributed some improvements to Reversi, adding the ability to change the board background color and use the Go stone graphics instead of the old circles.