7. Pour Vinegar On Them
Douse weeds with vinegar or a mixture of half water/half vinegar (or better yet, the leftover vinegar from a jar of pickles) and they'll be DOA a few days later. This is a good method for exterminating weeds with long taproots, including dandelions, dock, and plantain.
8. Torch Them:
You don't need actually set weeds on fire to kill them; quickly running a flame over them will usually cause them to wilt and die within days. You can buy a propane powered flame-thrower type weed scorcher at garden supply stores designed specifically for this purpose, or just use a handheld blow torch, depending on the volume of weeds you're dealing with. Be careful though not to torch poison ivy, since coming in contact with its smoke can trigger an allergic reaction just like touching it.
Related: 7 Smart Uses for Vinegar