First time I've done mapping using mainly just my iphone (and my motorbike). Just took a picture of each street name using the phone then went through them using Josm and the AgPifoJ plugin. Seems to work well enough, but I found that if I added them all at once in JOSM, I got really confused about exactly which was where. However, adding them one by one made a lot more sense (I also noticed that the photo icon stays grey until you click on it, when it turns red).
One odd thing, is that sometimes the photos often showed up at the last location I stopped. However, I think this may be more an iphone problem than a AgPifoJ one.
The webpage listing the unnamed streets is obviously invaluable doing something like this