Improvised use of newspaper thread:

http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=180575&page=1

rubber band, 101 uses and counting. that could be a thread by itself.

erasers, they can be easily shaped, not very concuctive, can take some heat, and are cheap. (the hard drive of my laptop is held securely in place with a strategic use of a tactical eraser.

empty soda bottle missing the cap and bottom works nicely as a funnel.

i know of a few improvised explosives. most are great distractions, but i don't think i should post that openly.

peanut butter. lubricant, bait, tasty, covers pretty much any smell on your breath.

Bar soap / Ivory? rubbed into gas tank leak as sealer.

Foil, even chewing gum foil wrapper, wrapped around blown fuse, re-insert fuse to complete circuit temporarily.

Stuck jar lid: if not going to recycle, pierce lid with church key [or anything else] to release vacuum for eay opening.

Tie a rope loop around two objects, put stick in loop about mid-way between the objects, and twist the stick perpendicular to the rope to bring two ends closer together - or if one end is fixed, drags unfixed object closer to fixed object, that is, pulls or lifts it.

No bait? Wrap a bit of shiny or colored wire, or thread the colored insulation slipped off a wire, onto your hook to attract fish.

We used to make gear bags out of old BDU bottoms. Cut the leg off, turn it inside out, sew the cut part shut, turn it right side out, and instant bag w/drawstring. Good little ditty bags.
When I used to shoot competetively, I used to use an old sock filled with sand as an elevation mechanism. In my prone shooting position, my offhand supports the rifle under the buttstock. By placing the butt of the rifle on the sock, I would then squeeze the sock to lower my scope, or relax it to raise it. I picked this neat little idea from a book somewhere, so it isnt mine-but I adapted it .

The vacum can be released by inserting something on the side of the lid and lifting. The handle of a spoon usually works. No need to destroy the lid.

Weirdest Macgyver tricks was probably to use an outdoors storage box (huge plastic box used for stuff like hammock pillows) for a crib. Empty box, take of the lid, wash it and persuade my mother (at her cabin, using her box!) that my daughter would be perfectly fine sleeping in the "crib".

The bottom drawer of dressers have long been used as baby cribs, esp useful for babies traveling to the homes of people who don't have babies. Pulled out but not removed, they don't sit right on a cold floor.

I've seen that trick where the drawer was pulled out but sitting on pillows on the floor.

The rounded end of the church key also works very well.

A stripped screw hole in wood can be repaired by sticking a wooden match or toothpick into the hole and broken off. Then insert the screw as usual.

Super glue can be used as stitches, either on cloth or your skin. (Disclaimer I am talking about minor cuts, not gaping wounds)