Verify what is staining your driveway. The primary suspects are usually oil, rust and tire skid marks.
Use a power washer on the driveway stain if it's old oil, rust or skid marks. This eliminates most, if not all of an otherwise troublesome stain. You can scrub off whatever is left over if necessary.
Pour cat litter onto an oil stain if it is fresh. Even if you do not have a cat, you will want to keep some around because it absorbs the oil very well.