Ethan Zonca of Protofusion writes:
The PogoProg is a small open source hardware pogo pin programming solution. The PogoProg does not need a physical connector on the board, it uses surface-mount pads for signals and thru-holes for alignment. Two standard footprints are available, the smallest of which takes up very little space–only 7.6mm x 1.2mm!
The PogoProg was originally designed for use with AVR microcontroller programming (using 6 pins), but this design can easily be repurposed for other programmers. Several footprints are available for this programming connector as shown on the test PCB above, but only two are recommended for real-world use: J1 (PogoProg Standard), J4 (PogoProg Micro)