Thanks for taking your time into reading this utterly boring subject! Hopefully I made it a bit less boring for you ;-). Yeah Tin-Eye is somewhat similar to Google Image Search. Unfortunately their database is not quite yet updated with the latest images, so Google Image Search is currently the way to go! (If you're using Chrome: right-click search image on Google)
Thanks for the tip on Pixabay (haven't heard of it yet) I'll be adding it to the list!