It's tough to use up an entire bar of soap because there's little to grasp when it's reduced to a tiny little wedge. Redditor localguy69 has a cool solution: turn those leftover soap bits into a shower gel.
The process is very easy and well-documented with photos. All you really need to do is boil some water, dump the soap bits in a food processor, add the boiling water and blend. When you're done, you'll have your homemade shower gel, which you can then stick in a bottle and use to get yourself clean.