I don’t know if very tiny tools like programmer adapters are very handy to use, but it is always fun to watch how tiny they can get. Philip took a vusbtiny programmer and squeeze it in to smallest PCB he could make.
So, he made USB connector directly on PCB by tracing pads on it. But to be sure, on other side he made footprint for Mini USB socket. If one fails there is a way out. Of course all parts are SMD except the 6-pin ISP connector. The board size come to be 12mm x 28mm and I think, there still is a space to squeeze a bit by making ISP header smaller (use 1mm instead of 2.54mm) or choosing smaller passives instead of 0805. But would such tool be normally useable?