Hexcord - Create presentations that you can livestream to YouTube
Device Shots - Generate high-resolution device mockups using a screenshot.
mmhmm - Bring yourself and your personality into your video chats
Facebook Design - Devices - Images and Sketch files of popular devices.
Excalideck - An app for authoring slide decks that look hand-drawn.
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.