I received two of the 23k256 breakout boards around 6 months ago and I've only just got round to building them. As I received two, I decided to try fitting a serial flash chip to one of them - I saw that microchip did a 32 Mbit flash with a similar layout, the only difference being that pin 3 had to be pulled high rather than not being connected. I haven't tested them yet, but all the connections seem good.
32Mbit serial flash
Nice work, good to see it working with a flash chip too. Thank you for sharing.