In the 2005 I published a guide (cafes-wifi.com) to 130 cafés in Paris with good free wifi and electrical plug. Tested myself.
Made it for my friends, nomad software workers.
But quickly became a big success among many nomads workers but also tourists in Paris who needed connexion.
In 2017 The website was closed.
Overall for a decade I had 10.000 unik visitors / month. Impactfull I would say