It's rare to find a mini kit so elegant, it deserves its own Haiku. A simple breakout, 2x3 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 pin 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)