4. A retired ladder as a rail, rack or plant stand
A wooden ladder that is no longer safe to climb is still a perfectly good frame of evenly spaced horizontal bars, which is an expensive thing to buy on purpose.
Make it safe first. Remove or fix any rope and hardware, check every rung is sound by pressing hard on each one, glue and screw any that move, and sand the whole thing including the rails — decades of hands and boots leave splinters. Finish with oil or paint. If the ladder is being retired because a rung actually broke, remove that rung entirely rather than trusting it.
Leaning against a bathroom wall it becomes a towel rail that holds four or five rolled towels and takes up almost no floor space. Secure the top to the wall with a small bracket or a length of wire so it cannot slide sideways, especially in a family bathroom.
In a bedroom it works as a blanket ladder or for hanging scarves and bags. In a kitchen, suspended horizontally from the ceiling on four chains and hooks, it becomes a pot rack and herb-drying rail — but fix the chains into joists, not plasterboard, and work out the loaded weight before you commit.
In a garden or on a balcony, a ladder leaned against a fence holds pots on each rung as a tiered plant stand, or supports climbing beans and sweet peas. Treated with exterior oil it will last several seasons outdoors.
A step ladder splayed open makes a freestanding plant stand or a display shelf if you screw boards across the corresponding rungs of each side. Check the hinge locks before loading it.