I'm surprised no one has mentioned this yet.
Long-handled Grass Clipping Shears
They look like this:
There is another kind that uses a much bigger handle, where the entire shaft is 2 separate pieces that you can use to cut mcuh thicker weeds.
Anyway, pros and cons of this:
###Pros
- No gas, electric, etc. Never runs out!
- Long so you don't have to bend over.
- Pretty inexpensive
- Easy to store
- Good for small yards
###Cons
- You will certainly tire out your hand if you have a large yard.