Yesterday I found this. It is a script created by Ejaz Mahmood to write Punjabi. What I like about Saanjo? Unlike Gurmukhi and Shahmukhi, it does represent tones. Though the creator doesn't call them tone markers, my understanding is that the "Supportive Signs" are indeed there to show tone. However, I may be wrong.
Also unlike Gurmukhi, which is an Abugida, and Shahmukhi, an Abjad, Saanjo is an alphabetic script. There is a guide to the script on the website for those who wish to learn.