Favorite non-magic item?
The humble 50′ rope.
How do I love thee:
1) Throw it down to let somebody climb out of a pit.
2) Put a grappling hook on it and use it to climb a wall.
3) Tie up a prisoner.
4) String together your mule-train carrying your loot.
5) Use it to pull open a door from afar.
6) Tie yourself to a tree or ship mast during a storm.
7) Lasso a wild animal.
8) Make a hammock high in a tree to avoid being eaten at night.
9) Use it as a trip wire or snare trap.
10) Swing across big rooms while playing swashbuckler.
11) Build a rope bridge.
12) Tie up a boat or raft.
I’m sure you can think of plenty more uses.
Rope: Never Leave the Inn Without It.
After that display of awesome suggestions, I do not think I could think of anything with as much versatility.