A couple of people have asked how they can make BAR LED boards like the ones we used for the blinken-lights demo
We use them all the time - they're really useful when you need to monitor the state of a byte-wide input or output.
We recently simplified the design by using a resistor array, and the boards are now really easy to make on strip-board.
Here is the new version, seen from the front and the back:
Here's the stripboard diagram, courtesy of Fritzing. The bar led is transparent, so you can see the breaks in the tracks beneath it; you can also see a couple of breaks just to the left of the BAR LED, and there are breaks in each track under the ULN2803.