Must-Have Equipment for a Small Home Gym

The question was simple: with only one square foot of floor space, what actually earns its keep in a home gym? The thread came back with a surprisingly consistent answer, skip the flashy one-trick machines and build around a few adjustable pieces that can do five jobs each. Bonus points if it also functions as your ab-day, arm-day, and "I refuse to leave the house" day equipment. Top 5, ranked by how often it came up.