It's rare to find a mini kit so elegant, it deserves its own Haiku. A simple breakout, 2x3 box header in the center, two 1x3's on the side. Plugs into any breadboard for neat wiring (in both nifty and clean senses of the word).
Comes with a quality mini PCB, a 2x3 box header and a small stick of 0.1" header. Requires some light soldering to use: plug the 2x3 in on the top and solder all six pins, then break the header in half and put each half into a breadboard to hold them steady. Place the breakout on top and solder the side pins. Will last you years and years.
Adafruit 6-pin AVR ISP Breadboard Adapter Mini Kit (17:28)