So your stuff ain't working right? Need to scope some signals on a lashed-together prototype? Try cutting your jumper wires in half.
Strip some insulation off the new ends, then solder them back together. Now, you can connect scope probes to the lines. In this case, I was debugging some I2C: wrong address, as it turned out. I stripped more insulation off the black jumper for the ground connection since it has to accommodate two ground clips.