Stop throwing away your bar soap leftovers
In the shower, I use bar-soap until it's too small to hold, then I end up stacking 3 or 4 of the small leftovers on top of eachother until the stack is big enough to press together to make a home-made, multi-colored bar. Another option would be to just throw out these seemingly useless slivers, but that seems like a waste.
I think a soft, pourous bag with a pull-string top would be useful to throw all the little leftover slivers in so they can be fully used again.