I would give credit to whatever site I got this recipe from, but I don't remember. So I'll say I got it from my mom, who emailed me the same recipe a few weeks ago...
This spray works awesome for killing those pesky dandelions that pop up in sidewalk cracks or along the garage...you know, the ones that you can't yank out of the ground :) .
WEED AND GRASS KILLER RECIPE
1 L vinegar
1/2 cup of salt
1 tbsp of liquid dish soap
Pour all ingredients into a spray bottle and shake very well. Works best on hot sunny days. Spray directly into the center of the dandelion, and make sure to spray the leaves. The dish soap helps the mixture stick to the leaves so it doesn't run off. Be careful, though, this will also kill grass or flowers or whatever else it happens to touch. Shake before every use.