I just found this IndieGogo campaign. I thought it might be of interest to alternative process photographers. It lets your smartphone tell you the UV index right where you are. This seems like it would be useful in determining exposure times for sun printing. I funded it and I hope you do too because it isn't yet to their goal. Considering I recently had problems with outdoor exposures due to a low UV index, I think this would be a really useful tool, so I really hope this gets funded and made.