> What would be the cheapest and easiest way to kill weeds that come up in my
> gravel driveway?
Well, that depends on how many weeds. If it's just a few, the old 'yank 'em out' would work best. For scattered clots of weeds, I'd go for boiling water followed by hand removal. If the whole shebang is covered with weeds, try Roundup, raking, repeat, and a pre-emergent.
Chris Owens