Noun Project is a life saver for presentations:
I don’t remember where I found out about it, but I use this website at every presentation for a couple of years already (at least 3½ years).
I’m familiar with the Noun Project. Gonna be honest, some of the stuff that crops up is totally horrendous. Either far too complicated, or oversimplified to the point of being unrecognizable, by some designed who thought they were being clever. In addition, many projects require some sort of consistent design, which takes quite some time to piece together on Noun Project. GitHub Octicons, for one example, are far more consistent for these and other applications—albeit a much more limited selection.