Like Chill's tarps, the black plastic mulch used by the commercial veggie growers has worked well for me. 4 ft wide, is covers two rows of plants, and completely eliminates hand weeding. And re-useable, with a bit of work - mine's going into it's fourth season. I lay irrigation drip tape beneath it before placing, and plant through it after it's down.
The best part - the use of the mulch resulted in plants twice the size of plants without it, in a controlled test my second year of growing.
Probably due to the lack of weed competition, and conserved moisture.