Have you coveted your neighbor's lemonbalm, mint, pelargoniums, or thymes? Maybe your plants have been added to someone else's covet list and you'd like to gift them their own. Easy fix!
(Insert disclaimer about asking neighbor if you can cut a small piece of their plant. Feel kind of hypocritical about disclaimer as you feel that anything growing over the sidewalk is fair game).
Plant Propagation Via Cutting (AKA Clone Plants on the Cheap!)
Scissors: make sure they're sharp and sturdy. I use kitchen scissors or pruning shears.
Container: watertight. Some folks like clear glass, but how many plants do you know that like to parade about with their roots exposed for all to see? I like dark glass because I figure it makes the roots happier. If you have to do the clear glass, I suggest covering the outside with a layer of aluminum foil or a crochet cozy.
Water: you'll fill the container about 1/2 full, making sure the cut surface is submerged but no leaves are in the water
Plant: pick one! or several!
Choose a healthy looking shoot, follow it down about 4-8 inches and make a sharp angled cut right below a set of leaves. Make sure that you remove the leaves from the bottom couple inches so they don't rot in the water. Speaking of water, plunk your prize down in that container and add an inch or two of water. There are rooting hormones you can carefully use, but many plants don't need it. A bit of willow bark tisane can help, too - although honestly I've only tried 1/2 a tsp with a couple lemonbalm cuttings, and lemonbalm roots crazy easy.
You can even do this with roses, I hear. I have yet to try it though. I have tried it successfully with tomatoes, lemonbalm, rosemary (although the roots took a long time, and half the cuttings rotted rather than rooting), and mint. With as crazy invasive as lemonbalm and mint are, I don't know why I thought I needed to make more.