I picked up a Sparkfun usb host shield for my Arduino Uno. It came without pins already installed. I was a bit intimidated to solder the pins myself; I've soldered before but have always made a hackjob of it.
The board before it was soldered (pins in place):
After (Flux residue is yet to be removed):
Not bad, considering this is my first crack at the right technique. I recommend you catch CuriousInventor's excellent YouTube video, "How and WHY to Solder Correctly." He nailed how I used to solder at the very beginning of the video.