tmux - tmux is a terminal multiplexer: it enables a number of terminals (or windows), each running a...
AppMockUp - Create the most compelling screenshots for your app.
GNU Screen - Screen is a full-screen window manager that multiplexes a physical terminal between several...
Placeit - Generate realistic product shots in seconds
mtm - Perhaps the smallest useful terminal multiplexer in the world.
Smartmockups - Create stunning product mockups, easily and online.