Here's a simple and natural weedkiller that you can make in your kitchen. I've used this a time or two and it really works! It's works best on broadleaf weeds and grass. Be sure to spray in full sun as it works by removing the moisture from the plant.
Mix a gallon of vinegar with 1 tablespoon of liquid dish detergent. The soap works to break down the waxy surface on the leaves, allowing the vinegar to remove the moisture. It also helps the solution to stick to the leaves, giving the vinegar time to kill the weed. Fill a spray bottle with the solution and spray the weeds thoroughly. The solution will kill any plant it comes in contact with so be careful not to over-spray neighboring plants. Small weeds will shrivel and die within 24 hours. This method doesn't work as well on deep rooted weeds, but is a great solution for the tender weeds that sprout in the Spring. A great alternative for those that don't like to use chemicals. Keep a spray bottle handy to take on those early morning walks around your yard.