A useful extension of my test probe adapter (http://www.thingiverse.com/thing:61466).
This is a simple jumper set that gives you a convenient set of mini probes for testing your breadboarded circuits.

Bill of Materials I get my parts from www.pololu.com but these are all standard 0.1" pitch connector parts so you can get them most anywhere. I've given the Pololu part numbers 2 -- Male-male 0.1" (2.54mm) jumper wires - Various lengths, see http://www.pololu.com/catalog/category/68 2 -- 1 pin crimp connector housing #1900 1 -- 2 pin crimp connector housing #1901 OR you can crimp up your own jumper wires using: 4 -- Male 0.1" (2.54mm) header pins #1931 wire Housings as above.